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DTC P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2 w/o RPO OSG


Object Number: 597623  Size: LF
Engine Controls Components
G104, H2O Sensors, O2 A B Fuses
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The powertrain control module (PCM) supplies a voltage of about 450 mV between the heated oxygen sensor (HO2S) high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.

The PCM monitors and stores the HO2S voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if the majority of the samples are out of the operating range.

The PCM monitors the HO2S voltage and detects if the voltage goes out of the bias range. If the PCM does not detect the voltage went out of the bias range, a diagnostic trouble code (DTC) sets.

Conditions for Running the DTC

    • No active mass air flow (MAF) DTCs
    • No active intake air temperature (IAT) DTCs
    • No active engine coolant temperature (ECT) DTCs
    • No active throttle position (TP) DTCs
    • No active injector DTCs
    • No active crank sensor DTCs
    • No active ignition control DTCs
    • The ignition voltage is more than 9.0 volts.
    • The engine run time is more than 70 seconds.
    • The fuel system is operating in Closed Loop.
    • The secondary air injection AIR), exhaust gas recirculation (EGR), and the catalyst diagnostics are not active.

Conditions for Setting the DTC

The HO2S signal voltage is steady between 410 mV and 490 mV for 2.5 minutes.

Action Taken When the DTC Sets

    • The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

    • The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
    • A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
    • A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
    • Use a scan tool in order to clear the MIL and the DTC.

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.

    • An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Heated Oxygen Sensor Wiring Repairs in Wiring Systems.
    • For an intermittent condition, refer to Symptoms .

Test Description

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

  1. The engine must be at the normal operating temperature before performing this test. For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616 . Using this kit prevents damage to the harness connector terminals. Refer to Using Connector Test Adapters in Wiring Systems.

  2. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you can not duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that the PCM recorded. This will isolate when the DTC failed. Refer to Symptoms .

  3. If the scan tool indicates the HO2S voltage goes below 200 mV, this indicates the HO2S circuits and PCM are OK.

  4. This step tests whether the low signal circuit from the PCM is OK. A voltage indicates the PCM and wiring are OK.

  5. Disconnecting the PCM allows using the DMM J 39200 in order to test continuity of the circuits. This aids in locating an open or shorted circuit. Refer to Testing for Continuity in Wiring Systems.

  6. Disconnecting the PCM allows using the DMM J 39200 in order to test continuity of the circuits. This aids in locating an open or shorted circuit. Refer to Testing for Continuity in Wiring Systems.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Important: Inspect the HO2S for being secure before proceeding with this DTC. A sensor that is loose could cause this DTC to set.

  1. Install a scan tool.
  2. Idle the engine at the normal operating temperature.
  3. Operate the engine above 1,200 RPM for two minutes.
  4. Monitor the HO2S voltage display on the Engine 1 Data List using the scan tool.

Does the scan tool indicate the HO2S voltage varying outside the specified range?

350-550 mV

Go to Step 3

Go to Step 4

3

  1. Turn ON the ignition leaving the engine OFF.
  2. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
  3. Turn OFF the ignition for 15 seconds.
  4. Idle the engine.
  5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in Freeze Frame/Failure Records as possible. Special operating conditions that need to be met before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
  6. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 4

Go to Diagnostic Aids

4

  1. Turn ON the ignition leaving the engine OFF.
  2. Disconnect the HO2S.
  3. Jumper the HO2S high and low (PCM side) signal circuits to a battery ground.
  4. Monitor the HO2S voltage using the scan tool.

Is the HO2S voltage below the specified value?

200 mV

Go to Step 8

Go to Step 5

5

  1. Remove the jumper wire from the HO2S low circuit.
  2. Measure the voltage from the HO2S low signal circuit to a battery ground using the DMM J 39200 .

Does the DMM indicate near the specified value?

5V

Go to Step 6

Go to Step 7

6

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement .
  3. Test the continuity of the HO2S high circuit. Refer to Testing for Continuity in Wiring Systems.
  4. Repair the open circuit if no continuity is indicated on the DMM. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the HO2S high circuit condition?

--

Go to Step 12

Go to Step 10

7

  1. Turn OFF the ignition.
  2. Disconnect the PCM connector C1 located on the same side as the manufacturer's logo. Refer to Powertrain Control Module Replacement .
  3. Test the continuity of the HO2S low circuit. Refer to Testing for Continuity in Wiring Systems.
  4. Repair the open or the poor connection if no continuity is indicated on the DMM. Refer to Wiring Repairs in Wiring Systems.

Did you find and correct the HO2S low circuit condition?

--

Go to Step 12

Go to Step 10

8

  1. Inspect the HO2S circuits for a poor connection at the HO2S harness connector. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection, repair the terminal as necessary. Refer to Connector Repairs in Wiring Systems.

Did you repair the condition?

--

Go to Step 12

Go to Step 9

9

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

Is the action complete?

--

Go to Step 12

--

10

  1. Inspect the HO2S circuits for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection, repair the terminal as necessary. Refer to Connector Repairs in Wiring Systems.

Did you repair the condition?

--

Go to Step 12

Go to Step 11

11

Important:: Program the replacement PCM. Refer to Powertrain Control Module Replacement .

Replace the PCM.

Is the action complete?

--

Go to Step 12

--

12

  1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
  2. Idle the engine at the normal operating temperature.
  3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 13

Go to Step 2

13

Select the Capture Info option and the Review Info option using the scan tool.

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

--

Go to the applicable DTC table

System OK

DTC P0140 HO2S Circuit Insufficient Activity Bank 1 Sensor 2 w/ RPO OSG


Object Number: 597836  Size: LF
Engine Controls Components
G104, H2O Sensors, O2 A B Fuses
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The heated oxygen sensor (HO2S) is a sensor designed to create a voltage relative to the oxygen content in the engine exhaust stream. The control module supplies the HO2S with signal high and low circuits. Ignition voltage and ground are supplied to the HO2S heater by independent circuits. The oxygen content of the exhaust indicates when the engine is operating lean or rich. When the HO2S detects that the engine is operating rich, the signal voltage is high and decreases the signal voltage as the engine runs leaner. This oscillation above and below the bias voltage sometimes referred to as activity or switching, can be monitored with the HO2S signal voltage.

The HO2S contains a heater that is necessary in order to quickly warm the sensor to operating temperature and to maintain the operating temperature during extended idle conditions. The HO2S needs to be at a high temperature in order to produce a voltage. Once the HO2S has reached operating temperature, the control module monitors the HO2S bias, or reference, voltage as well as the HO2S signal voltage for Closed Loop fuel control. During normal Closed Loop fuel control operation, the control module will add fuel or enrich the mixture when the HO2S detects a lean exhaust content and subtract fuel, or lean-out the mixture when the HO2S detects a rich exhaust condition.

Certain vehicle models utilize an oxygen sensor after the catalytic converter in order to monitor catalyst efficiency.

This diagnostic trouble code (DTC) determines if the HO2S is functioning properly by checking for an adequate number of HO2S voltage transitions above and below the bias range of 300-600 mV. This DTC sets when the powertrain control module (PCM) fails to detect a minimum number of voltage transitions above and below the bias range during the test period. Possible causes of this DTC are listed below:

    • An open or a short to voltage on either the HO2S signal or HO2S low circuits
    • A malfunctioning HO2S
    • A problem in the HO2S heater or its circuit
    • A poor HO2S ground
    • An open HO2S low reference circuit

Conditions for Running the DTC

    • No active throttle position (TP) sensor DTCs
    • No active evaporative emission (EVAP) system DTCs
    • No active intake air temperature (IAT) sensor DTCs
    • No active manifold absolute pressure (MAP) sensor DTCs
    • No active engine coolant temperature (ECT) sensor DTCs
    • No active mass air flow (MAF) sensor DTCs
    • No active misfire DTCs
    • No intrusive test in progress
    • No device controls active
    • The system voltage is between 11.7-17 volts.
    • The engine has been running for more than 2 minutes.
    • The decel fuel cut-off mode (DFCO) is not active.
    • The ECT is more than 58°C (137°F).
    • The MAF is more than 13 g/s.
    • DTC P0135 not active
    • The system is in Closed Loop.

Conditions for Setting the DTC

The heated oxygen sensor (HO2S) voltage is between 300 mV and 600 mV for more than 1 minute.

Action Taken When the DTC Sets

    • The control module illuminates the malfunction indicator lamp (MIL) if a failure is detected during 2 consecutive key cycles.
    • The control module sets the DTC and records the operating conditions at the time the diagnostic failed. The failure information is stored in the scan tool Freeze Frame/Failure Records.

Conditions for Clearing the MIL or DTC

    • The control module turns OFF the MIL after 3 consecutive drive trips when the test has run and passed.
    • A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles. A warm-up cycle occurs when the coolant temperature has risen 22°C (40°F) from the startup coolant temperature and the engine coolant reaches a temperature that is more than 70°C (158°F) during the same ignition cycle.
    • Use a scan tool in order to clear the DTCs.

Diagnostic Aids

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

    • A malfunctioning HO2S heater or heater circuit -- With the ignition ON and the engine OFF, the HO2S voltage displayed on a scan tool should gradually drop to below 0.150 volt, indicating that the heater works properly. If not, disconnect the HO2S and connect a test lamp between the terminals C and D. If the test lamp does not light, repair the open in the HO2S ground circuit or the HO2S ignition positive voltage circuit. If the test lamp lights, replace the HO2S.
    • The intermittent test -- Use a scan tool in order to monitor this HO2S signal voltage. Move the related connectors and the wiring harness with a warm engine running at part throttle in Closed Loop. If the failure is induced, the HO2S signal voltage reading changes from its normal fluctuating voltage above 600 mV and below 300 mV, to a fixed value around 450 mV. This may help to isolate the location of the malfunction.

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.

  1. This step checks for proper sensor activity. When in Closed Loop fuel control, the HO2S voltage should rapidly swing above and below the bias voltage.

  2. This step checks the PCM and the HIGH and LOW circuits between the PCM and the HO2S connector for proper operation.

  3. This step checks for proper HO2S heater circuit operation up to the HO2S connector.

Step

Action

Value(s)

Yes

No

1

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

  1. Clear the DTC Information from the PCM.
  2. Reset the fuel trim values.
  3. Start and idle the engine until normal operating temperature is reached.
  4. Using a scan tool, monitor the HO2S voltage for the sensor that applies to this DTC.

Is the HO2S voltage fixed within the voltage range specified?

300-600 mV

Go to Step 4

Go to Step 3

3

The condition that set this DTC is not present. This DTC may have been set by one of the following conditions:

    • HO2S connector water intrusion
    • An intermittently open HO2S HIGH signal circuit
    • An intermittently open HO2S LOW circuit
    • An HO2S LOW circuit with high resistance to ground
    • PCM ground circuits with high resistance to ground
    • An inoperative HO2S heater
    • Poor HO2S or PCM connector terminal contact
    • An exhaust system leak, typically within 30 cm (12 in) up-stream of the HO2S
    • A defective HO2S

Repair any of the above conditions as necessary.

Did you find a problem?

--

Go to Step 15

Go to Diagnostic Aids

4

  1. Turn OFF the ignition.
  2. Disconnect the HO2S connector for the sensor that applies to this DTC.
  3. Jumper the HO2S LOW circuit to a known good ground.
  4. Jumper the HO2S HIGH signal circuit to a known good ground.
  5. Turn ON the ignition, with the engine OFF.
  6. Using a scan tool, monitor the HO2S voltage for the sensor that applies to this DTC.

Is the voltage less than the specified value?

20 mV

Go to Step 7

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Remove the jumpers from the HO2S terminals.
  3. Disconnect the PCM connector containing the HO2S HIGH and LOW circuits.
  4. Measure the continuity of the following with a DMM:
  5. • The HO2S high signal circuit and either of the HO2S low circuits between the PCM connector terminal and the HO2S connector terminal
    • Between both HO2S Low circuits at the PCM connector terminal

Is the resistance of both circuits less than the specified value?

5 ohms

Go to Step 6

Go to Step 11

6

  1. Check for proper PCM connector terminal contact.
  2. Repair PCM terminals as necessary. Refer to Connector Repairs in Wiring Repairs.

Did you find a problem?

--

Go to Step 15

Go to Step 14

7

  1. Remove the jumpers from the HO2S terminals.
  2. Connect a test lamp between the HO2S heater ignition positive voltage and heater ground circuit terminals.
  3. Ensure the ignition is ON, with the engine OFF.

Is the test lamp ON?

--

Go to Step 9

Go to Step 8

8

Repair the HO2S heater ignition positive voltage or ground circuit. Refer to Wiring Repairs in Wiring Systems. Probable causes include the following:

    • An open circuit
    • High circuit resistance
    • Poor ground connection
    • A blown heater fuse, other DTCs should set

Is the action complete?

--

Go to Step 15

--

9

  1. Check for exhaust system leaks upstream of the suspect HO2S.
  2. The leak may be very small and typically be within 30 cm (12 in.) of the suspect HO2S.

  3. Repair the exhaust as necessary.

Did you find a problem?

--

Go to Step 15

Go to Step 10

10

Inspect for one of the following conditions that may cause the reference voltage to be skewed:

    • A poor HO2S connector terminal contact
    • An open sensor harness LOW circuit
    • A sensor harness LOW circuit with high resistance
    • A poor PCM ground connection
    • High PCM ground circuit resistance
    • An open in the HO2S low circuit between the splice and either HO2S low circuit PCM connector

Did you find and correct the condition?

--

Go to Step 12

--

11

Repair the circuit that measured high resistance. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 15

--

12

  1. Remove the HO2S from the exhaust.
  2. Clean the HO2S mounting treads.
  3. Apply anti-seize compound 561 3695 or equivalent to the sensor treads.
  4. Tighten the HO2S to the proper torque. Refer to Heated Oxygen Sensor Replacement - Bank 1 .
  5. Using a DMM remeasure the resistance between the HO2S LOW circuit terminal and a PCM ground circuit terminal.

Is the resistance less than the specified value?

500 ohms

Go to Step 15

Go to Step 13

13

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

Is the action complete?

--

Go to Step 15

--

14

Important:: The replacement PCM must be programmed.

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 15

--

15

  1. Using the scan tool, clear the DTCs.
  2. Start the engine.
  3. Allow the engine to idle until the engine reaches normal operating temperature.
  4. Select DTC and the Specific DTC function.
  5. Enter the DTC number which was set.
  6. Operate the vehicle within the Conditions for Setting this DTC, until the scan tool indicates the diagnostic Ran.

Does the scan tool indicate the diagnostic Passed?

--

Go to Step 16

Go to Step 2

16

Does the scan tool display any additional undiagnosed DTCs?

--

Go to the applicable DTC table

System OK