DTC P0133 or P0153. Cadillac Escalade 2002

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 2002 🢒 Escalade 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC P0133 or P0153

DTC P0133 or P0153 4.8L or 5.3L w/Case Grounded HO2S

Circuit Description

This diagnostic applies only to vehicles built with case grounded heated oxygen sensors (HO2S). To identify the HO2S, refer to Engine Controls Component Views .

The powertrain control module (PCM) continuously monitors the HO2S activity for 100 seconds. During the monitor period, the PCM counts the number of times that the HO2S responds from rich-to-lean and from lean-to-rich and adds the amount of time necessary to complete all transitions. With this information, the PCM can determine the average time for all transitions. If the average response time is too slow, a diagnostic trouble code (DTC) sets.

The PCM determines the lean to rich transition when the HO2S voltage changes from less than 300 mV to more than 600 mV. The PCM determines the rich to lean transition when the HO2S voltage changes from more than 600 mV to less than 300 mV.

Conditions for Running the DTC

•

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0116, P0118, P0121, P0122, P0123, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0300, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1404, , P1441, P1514, P1515, P1516, P1517, or P1518 are not set.

•	The engine coolant temperature (ECT) is more than 65°C (149°F).

•	The engine run time is more than 160 seconds.

•	The evaporative emission (EVAP) purge solenoid command is more than 1 percent.

•	The mass air flow (MAF) is between 23-50 g/s.

•	The engine speed is between 1,200-3,000 RPM.

•	For vehicles without throttle-actuated control (TAC), the throttle position (TP) is more than 5 percent.

•	For vehicles with TAC, the TP indicated angle is 5 percent more than the value observed at idle.

•	The vehicle is operating in Closed Loop.

•	The ignition 1 signal is between 9-18 volts.

•	The fuel tank level remaining is more than 10 percent.

•	Intrusive tests are not in progress.

•	The scan tool output controls are not active.

•	The above conditions are met for 100 seconds.

Conditions for Setting the DTC

The rich-to-lean and lean-to-rich response time average is more than a calibrated value.

Action Taken When the DTC Sets

•	The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

•	The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

•	Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

•	This diagnostic only runs once per ignition cycle.

•	A malfunction in the HO2S heater circuits causes a DTC to set. Inspect the HO2S heater circuits for intermittent opens and faulty connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

•	An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provide the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems.

•

Using the Freeze Frame/Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass or a fail. Operate the vehicle within the same Freeze Frame conditions such as RPM, load, vehicle speed, temperature, etc. that you observed. This will isolate when the DTC failed. For an intermittent condition, refer to Intermittent Conditions .

Test Description

The numbers below refer to the step numbers on the diagnostic table.

This step determines if the fault is present. This test may take 5 minutes for the diagnostic to run.

When DTCs P0133 and P0153 are set at the same time, it is a good indication that a fuel contamination problem is present.

An exhaust leak 15.2-30.4 cm (6-12 inches) away from the HO2S can cause a DTC to set.

This step tests whether a good ground circuit is available.

This step tests the integrity of the low signal circuit to the PCM.

Certain RTV silicone gasket materials emit vapors that can contaminate the HO2S. There is also a possibility of silicone-contamination caused by silicone in the fuel. If the sensors appear to be contaminated by silicone and all the silicone sealant is a non silicone base, advise the customer to try a different fuel company. A missing fuel filler restrictor indicates the customer may have used leaded fuel.

Step

Action

Values

Yes

Important: This diagnostic applies only to vehicles built with case grounded HO2S. To identify the HO2S, refer to Engine Controls Component Views .

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: If any DTCs are set except DTC P0133 or P0153, refer to those DTCs before proceeding with this diagnostic table.

Install a scan tool.
Idle the engine at the normal operating temperature.
Operate the vehicle within the parameters specified under Conditions for Running the DTC in the supporting text.
Use the scan tool in order to monitor the diagnostic trouble code (DTC) information.

Did DTC P0133 or P0153 fail this ignition?

Go to Step 3

Go to Diagnostic Aids

Did both DTC P0133 and P0153 fail this ignition?

Go to Step 8

Go to Step 4

Inspect for an exhaust system leak. Refer to Exhaust Leakage in Engine Exhaust. After you inspect the exhaust system return to this diagnostic.
Repair any exhaust leak as necessary.

Did you find and correct the condition?

Go to Step 14

Go to Step 5

Inspect the following items:

•	Ensure that the HO2S is securely installed.

•	Inspect for corrosion on the terminals.

•	Test the terminal tension at the HO2S and at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

•	Inspect for damaged wiring.

Did you find and correct the condition?

Go to Step 14

Go to Step 6

Disconnect the HO2S.
Jumper the HO2S low signal circuit to a known good ground.
Use the scan tool in order to monitor the HO2S voltage on the Engine 1 Data List.

Is the voltage within the specified range?

350-550 mV

Go to Step 7

Go to Step 10

Jumper the HO2S high and low signal circuits to battery ground.
Use the scan tool in order to monitor the HO2S voltage.

Is the voltage less than the specified value?

200 mV

Go to Step 13

Go to Step 9

Important: Determine and correct the cause of the contamination before replacing a sensor. Inspect for the following conditions:

•	Any fuel contamination

•	The use of improper RTV sealant

•	Any excessive engine oil and coolant consumption

Replace the affected heated oxygen sensor. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or to Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .

Did you complete the replacement?

Go to Step 14

Remove the jumper wire from the HO2S low signal circuit.
Use a DMM in order to measure the voltage from the HO2S low signal circuit to battery ground.

Is the voltage near the specified value?

5 V

Go to Step 12

Go to Step 11

Repair the high signal circuit for a short to ground or a short to voltage. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

Repair the open in the HO2S low signal circuit or repair the poor PCM connections. Refer to Heated Oxygen Sensor Wiring Repairs or Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

Repair the HO2S high signal circuit for an open or repair the poor PCM connections. Refer to Heated Oxygen Sensor Wiring Repairs or Connector Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 14

Replace the HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .

Did you complete the replacement?

Go to Step 14

Use the scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 15

Go to Step 2

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK

DTC P0133 or P0153 4.8L or 5.3L w/Isolated Grounded HO2S

Circuit Description

This diagnostic applies only to vehicles built with isolated grounded heated oxygen sensors (HO2S). To identify the HO2S, refer to Engine Controls Component Views .

The powertrain control module (PCM) continuously monitors the HO2S activity for 100 seconds. During the monitor period, the PCM counts the number of times that the HO2S responds from rich to lean and from lean to rich and adds the amount of time necessary to complete all transitions. With this information, the PCM can determine the average time for all transitions. If the average response time is too slow, a diagnostic trouble code (DTC) sets.

Conditions for Running the DTC

•

DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0117, P0116, P0118, P0121, P0122, P0123, P0131, P0132, P0134, P0135, P0151, P0152, P0154, P0155, P0200, P0300, P0401, P0404, P0405, P0440, P0442, P0446, P0452, P0453, P1120, P1125, P1220, P1221, P1258, P1404, P1441, P1514, P1515, P1516, P1517, or P1518 are not set.

•	The engine coolant temperature (ECT) is more than 65°C (149°F).

•	The engine run time is more than 160 seconds.

•	The evaporative emission (EVAP) purge solenoid command is more than 1 percent.

•	The mass air flow (MAF) is between 23-50 g/s.

•	The engine speed is between 1,200-3,000 RPM.

•	For vehicles without throttle-actuated control (TAC), the throttle position (TP) is more than 5 percent.

•	For vehicles with TAC, the TP indicated angle is 5 percent more than the value observed at idle.

•	The vehicle is operating in Closed Loop.

•	The ignition 1 signal is between 9-18 volts.

•	The fuel tank level remaining is more than 10 percent.

•	The fuel alcohol content is less than 90 percent.

•	Intrusive tests are not in progress.

•	The scan tool output controls are not active.

•	The above conditions are met for 100 seconds.

Conditions for Setting the DTC

The rich-to-lean and lean-to-rich response time average is more than a calibrated value.

Action Taken When the DTC Sets

•	The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

Conditions for Clearing the MIL/DTC

•	The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

•	Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

Important: Never solder the HO2S wires. For proper wire and connector repairs, refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Inspect for the following conditions:

•	Inspect for an improperly installed air cleaner outlet duct

•	Inspect the air cleaner outlet duct for a collapsed duct, restrictions, or a missing or plugged air filter

•	Inspect the throttle body and the intake manifold for vacuum leaks.

•	Inspect for a damaged or blocked throttle body inlet.

•	Inspect the exhaust system for corrosion, leaks, or loose or missing hardware. Refer to Exhaust Leakage in Engine Exhaust.

•	Verify that the HO2S is installed securely and the pigtail harness is not contacting the exhaust manifold or wires.

•	Inspect for any HO2S contamination.

•	Inspect the vacuum hoses for splits, kinks, and proper connections.

•	Test for excessive water, alcohol, or other contaminants in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Verify that the PCM sensor grounds are clean, tight, and properly positioned.

An intermittent may be caused by any of the following conditions:

•	A poor connection

•	Rubbed through wire insulation

•	A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

After the ignition is turned ON, the HO2S heater heats up causing the HO2S signal voltage to either increase or decrease. This indicates that the HO2S heater is OK.

If the HO2S voltage is varying outside the specified range, the condition is not present.

If the test lamp illuminates, the low reference circuit between the HO2S and PCM terminal C1-63 is OK and the PCM low reference terminal is OK.

If the voltage is below the specified value, the high signal circuit, the low reference circuit, and the PCM are OK.

The opposite bank HO2S must be disconnected to isolate a short to ground in the HO2S heater ignition 1 voltage circuit.

Resistance within the specified range indicates the HO2S heater is OK.

Step

Action

Values

Yes

Important: This diagnostic applies only to vehicles built with isolated grounded HO2S. To identify the HO2S, refer to Engine Controls Component Views .

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: Allow the engine to cool for one-half hour before proceeding with this diagnostic. This allows the HO2S signal voltage to return to bias voltage, approximately 447 mV.

Install a scan tool.
Turn ON the ignition, with the engine OFF.
Immediately observe the affected HO2S voltage for 2 minutes.

Does the HO2S voltage go from bias voltage to more than or less than the specified range?

300-600 mV

Go to Step 3

Go to Step 5

Start the engine.
Allow the engine to reach operating temperature.
Raise and hold the engine speed at 1,200 RPM for 2 minutes.
Observe the HO2S voltage with a scan tool.

Is the HO2S voltage varying outside the specified range?

350-550 mV

Go to Step 4

Go to Step 5

Observe the Freeze Frame/Failure Records data for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text or as close to the Freeze Frame/Failure Records data that you observed.

Does the DTC fail this ignition?

Go to Step 5

Go to Intermittent Conditions

Are both DTCs P0133 and P0153 set?

Go to Step 6

Go to Step 7

Turn OFF the ignition.
Disconnect the bank 1 sensor 1 HO2S connector.
Probe the HO2S low reference circuit with a test lamp that is connected to battery positive.

Does the test lamp illuminate?

Go to Step 11

Go to Step 10

Turn OFF the ignition.
Disconnect the affected HO2S connector.
Jumper the HO2S high signal circuit to the low reference circuit.
Turn ON the ignition, with the engine OFF.
Observe the HO2S voltage with a scan tool.

Is the HO2S voltage less than the specified value?

200 mV

Go to Step 11

Go to Step 8

Turn OFF the ignition.
Disconnect the PCM connector containing the HO2S high signal circuit. Refer to Powertrain Control Module Replacement .
Test the HO2S high signal circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 9

Test for an open between terminal A of the affected sensor harness connector and one of the following PCM terminals:

•	If DTC P0133 is set, use C1-29

•	If DTC P0153 is set, use C1-26

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 19

Disconnect the PCM connector containing the HO2S low reference circuit. Refer to Powertrain Control Module Replacement .
Test the low reference circuit for an open between HO2S bank 1 sensor 1 terminal A and PCM terminal C1-63.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 19

Remove the jumper from the previous step, if applicable.

Is the O2A fuse open?

Go to Step 14

Go to Step 12

Turn ON the ignition, with the engine OFF.
Probe the affected HO2S ignition 1 voltage circuit with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 13

Go to Step 20

Connect a test lamp between the affected HO2S ignition 1 voltage circuit and the HO2S heater ground circuit.
Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

Go to Step 17

Go to Step 21

Disconnect the opposite bank HO2S pigtail connector.
Test the HO2S ignition 1 voltage circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Replace the O2A fuse.

Did you find and correct a short to ground in the ignition 1 voltage circuit?

Go to Step 24

Go to Step 15

Important: Perform the following test on HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1. A condition in either sensor will cause this DTC to set.

Test the HO2S ignition 1 voltage circuit, sensor side, for a short to the HO2S body. Refer to Circuit Testing in Wiring Systems.

Did you find the condition?

Go to Step 22

Go to Step 16

Important: Perform the following test on HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1. A condition in either sensor will cause this DTC to set.

Measure the resistance between the HO2S ignition 1 voltage circuit, sensor side, and the HO2S heater ground circuit, sensor side. Refer to Circuit Testing in Wiring Systems.

Does the resistance of either sensor measure above or below the specified range?

2-50 ohms

Go to Step 22

Go to Intermittent Conditions

Important: Before replacing the suspected HO2S, inspect and remove any source of contamination.

Inspect for the following conditions:

•	The use of incorrect silicon RTV sealant

•	An engine coolant leak into the combustion chamber

•	Excessive engine oil consumption

•	Fuel contamination

•	An exhaust system leak or restriction

•	Incorrect fuel pressure

Did you find and correct the condition?

Go to Step 24

Go to Step 18

Inspect for poor connections at the harness connector of the affected HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 22

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 24

Go to Step 23

Repair the open in the ignition 1 voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 24

Repair the open in the HO2S heater ground circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 24

Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .

Did you complete the replacement?

Go to Step 24

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 24

Use the scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 25

Go to Step 2

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK

DTC P0133 or P0153 6.0L w/Isolated Grounded HO2S

Circuit Description

This diagnostic applies only to vehicles built with isolated grounded heated oxygen sensors (HO2S). To identify the HO2S, refer to Engine Controls Component Views .

The powertrain control module (PCM) continuously monitors the HO2S activity for 100 seconds. During the monitor period, the PCM counts the number of times that the HO2S responds from rich to lean and from lean to rich and adds the amount of time necessary to complete all transitions. With this information, the PCM can determine the average time for all transitions. If the average response time is too slow, a diagnostic trouble code (DTC) sets.

Conditions for Running the DTC

•

•	The engine coolant temperature (ECT) is more than 65°C (149°F).

•	The engine run time is more than 160 seconds.

•	The evaporative emission (EVAP) purge solenoid command is more than 1 percent.

•	The mass air flow (MAF) is between 23-50 g/s.

•	The engine speed is between 1,200-3,000 RPM.

•	For vehicles without throttle-actuated control (TAC), the throttle position (TP) is more than 5 percent.

•	For vehicles with TAC, the TP indicated angle is 5 percent more than the value observed at idle.

•	The vehicle is operating in Closed Loop.

•	The ignition 1 signal is between 9-18 volts.

•	The fuel tank level remaining is more than 10 percent.

•	The fuel alcohol content is less than 90 percent.

•	Intrusive tests are not in progress.

•	The scan tool output controls are not active.

•	The above conditions are met for 100 seconds.

Conditions for Setting the DTC

The rich-to-lean and lean-to-rich response time average is more than a calibrated value.

Action Taken When the DTC Sets

•	The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.

•

Conditions for Clearing the MIL/DTC

•	The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

•	A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

•	A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

•	Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

Important: Never solder the HO2S wires. For proper wire and connector repairs, refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Inspect for the following conditions:

•	Inspect for an improperly installed air cleaner outlet duct

•	Inspect the air cleaner outlet duct for a collapsed duct, restrictions, or a missing or plugged air filter

•	Inspect the throttle body and the intake manifold for vacuum leaks.

•	Inspect for a damaged or blocked throttle body inlet.

•	Inspect the exhaust system for corrosion, leaks, or loose or missing hardware. Refer to Exhaust Leakage in Engine Exhaust.

•	Verify that the HO2S is installed securely and the pigtail harness is not contacting the exhaust manifold or wires.

•	Inspect for any HO2S contamination.

•	Inspect the vacuum hoses for splits, kinks, and proper connections.

•	Test for excessive water, alcohol, or other contaminants in the fuel. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Verify that the PCM sensor grounds are clean, tight, and properly positioned.

An intermittent may be caused by any of the following conditions:

•	A poor connection

•	Rubbed through wire insulation

•	A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

If a repair is necessary, then refer to Wiring Repairs or Connector Repairs in Wiring Systems.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

After the HO2S heater is commanded ON, the HO2S heater heats up causing the HO2S signal voltage to either increase or decrease. This indicates that the HO2S heater is OK.

If the HO2S voltage is varying outside the specified range, the condition is not present.

If the test lamp illuminates, the low reference circuit between the HO2S and PCM terminal C1-63 is OK and the PCM low reference terminal is OK.

If the voltage is below the specified value, the high signal circuit, the low reference circuit, and the PCM are OK.

The opposite bank HO2S must be disconnected to isolate a short to ground in the HO2S heater high control circuit.

Resistance within the specified range indicates the HO2S heater is OK.

Step

Action

Values

Yes

Important: This diagnostic applies only to vehicles built with isolated grounded HO2S. To identify the HO2S, refer to Engine Controls Component Views .

Schematic Reference: Engine Controls Schematics

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

Important: Allow the engine to cool for one-half hour before proceeding with this diagnostic. This allows the HO2S signal voltage to return to bias voltage, approximately 447 mV.

Install a scan tool.
Turn ON the ignition, with the engine OFF.
Command the HO2S heater ON with a scan tool.
Immediately observe the affected HO2S voltage for 2 minutes.

Does the HO2S voltage go from bias voltage to more than or less than the specified range?

300-600 mV

Go to Step 3

Go to Step 5

Start the engine.
Allow the engine to reach operating temperature.
Raise and hold the engine speed at 1,200 RPM for 2 minutes.
Observe the HO2S voltage with a scan tool.

Is the HO2S voltage varying outside the specified range?

350-550 mV

Go to Step 4

Go to Step 5

Observe the Freeze Frame/Failure Records data for this DTC.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, or as close to the Freeze Frame/Failure Records data that you observed.

Does the DTC fail this ignition?

Go to Step 5

Go to Intermittent Conditions

Are Both DTCs P0133 and P0153 set?

Go to Step 6

Go to Step 7

Turn OFF the ignition.
Disconnect the bank 1 sensor 1 HO2S connector.
Probe the HO2S low reference circuit with a test lamp that is connected to battery positive.

Does the test lamp illuminate?

Go to Step 11

Go to Step 10

Turn OFF the ignition.
Disconnect the affected HO2S connector.
Jumper the HO2S high signal circuit to the low reference circuit.
Turn the ignition ON, with the engine OFF.
Observe the HO2S voltage with a scan tool.

Is the HO2S voltage less than the specified value?

200 mV

Go to Step 11

Go to Step 8

Turn OFF the ignition.
Disconnect the PCM connector containing the HO2S high signal circuit. Refer to Powertrain Control Module Replacement .
Test the HO2S high signal circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 9

Test for an open between terminal A of the affected sensor harness connector and one of the following PCM terminals:

•	If DTC P0133 is set use C1-29

•	If DTC P0153 is set use C1-26

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 18

Disconnect the PCM connector containing the HO2S low reference circuit. Refer to Powertrain Control Module Replacement .
Test the low reference circuit for an open between HO2S bank 1 sensor 1 terminal A and PCM terminal C1-63.

Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 18

If applicable, remove the jumper from the previous step.
Disconnect the opposite bank HO2S connector.
Perform the following:

•	If only one DTC is set, P0133 or P0153, probe the affected HO2S heater high control circuit with a test lamp that is connected to a good ground.

•	If both DTC P0133 and P0153 are set, probe HO2S bank 1 sensor 1 heater high control circuit with a test lamp that is connected to a good ground.

Command the HO2S heater ON with a scan tool.

Does the test lamp illuminate?

Go to Step 12

Go to Step 13

Connect a test lamp between the affected HO2S heater high control circuit and the HO2S heater low reference circuit.
Command the HO2S heater ON with a scan tool.

Does the test lamp illuminate?

Go to Step 14

Go to Step 16

Disconnect the PCM connector containing the HO2S heater high control circuit. Refer to Powertrain Control Module Replacement .
Test the HO2S heater high control circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 18

Important: Perform the following test on HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1. A condition in either sensor will cause this DTC to set.

Test the HO2S heater high control circuit, sensor side, for a short to the HO2S body. Refer to Circuit Testing in Wiring Systems.

Did you find the condition?

Go to Step 21

Go to Step 15

Important: Perform the following test on HO2S bank 1 sensor 1 and HO2S bank 2 sensor 1. A condition in either sensor will cause this DTC to set.

Measure the resistance between the HO2S heater high control circuit, sensor side, and the HO2S heater low reference circuit, sensor side. Refer to Circuit Testing in Wiring Systems.

Does the resistance of either sensor measure above or below the specified range?

2-50 ohms

Go to Step 21

Go to Step 17

Disconnect the PCM connector containing the HO2S heater low reference circuit. Refer to Powertrain Control Module Replacement .
Test the HO2S heater low reference circuit for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 18

Important: Before replacing the suspected HO2S, inspect and remove any source of contamination.

Inspect for the following conditions:

•	The use of incorrect silicon RTV sealant

•	An engine coolant leak into the combustion chamber

•	Excessive engine oil consumption

•	Fuel contamination

•	An exhaust system leak or restriction

•	Incorrect fuel pressure

Did you find and correct the condition?

Go to Step 22

Go to Step 19

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 20

Inspect for poor connections at the harness connector of the affected HO2S. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 22

Go to Step 19

Replace the PCM. Refer to Powertrain Control Module Replacement .

Did you complete the replacement?

Go to Step 22

Replace the affected HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 1 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 1 .

Did you complete the replacement?

Go to Step 22

Use the scan tool in order to clear the DTCs.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

Go to Step 23

Go to Step 2

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK