DTC P0140 or P0160 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) supplies a voltage of about 450 mV between the 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
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, 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 run time is more than 409 seconds. |
| • | The vehicle is operating in Closed Loop. |
| • | The ignition 1 signal is between 9-18 volts. |
| • | Intrusive tests are not in progress. |
| • | The scan tool output controls are not active. |
Conditions for Setting the DTC
| • | The HO2S voltage is steady between 410-490 mV for 150 seconds. |
| • | The TP changes more than 5 percent within 1 second, 6 times. |
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.
| • | 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 Intermittent Conditions . |
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 voltage is below the specified value, the high signal circuit, the low signal circuit, and the PCM are OK.
-
If the voltage is above the specified value, the low signal circuit is 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 | No |
|---|---|---|---|---|
|
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 | ||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |
|
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.
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 | |
Is the HO2S voltage outside the specified range? | 410-490 mV | Go to Step 4 | Go to Step 5 | |
4 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions |
Is the HO2S voltage less than the specified value? | 200 mV | Go to Step 9 | Go to Step 6 | |
Is the voltage above the specified value? | 4 V | Go to Step 7 | Go to Step 8 | |
7 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 |
8 |
Did you find and correct the condition? | -- | Go to Step 21 | Go to Step 16 |
9 | Remove the jumpers from the previous step. Is the O2B fuse open? | -- | Go to Step 12 | Go to Step 10 |
10 |
Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 17 |
11 |
Does the test lamp illuminate? | -- | Go to Step 15 | Go to Step 18 |
Did you find and correct a short to ground in the ignition 1 voltage circuit? | -- | Go to Step 21 | Go to Step 13 | |
13 |
Important: Perform the following test on HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2. 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 19 | Go to Step 14 |
|
Important: Perform the following test on HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2. 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 19 | Go to Intermittent Conditions | |
15 | 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 21 | Go to Step 19 |
16 | 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 21 | Go to Step 20 |
17 | 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 21 | -- |
18 | Repair the open in the HO2S heater ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 21 | -- |
19 | Replace the affected HO2S refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 . Did you complete the replacement? | -- | Go to Step 21 | -- |
20 | Replace the PCM. Refer to Powertrain Control Module Replacement Did you complete the replacement? | -- | Go to Step 21 | -- |
21 |
Does the DTC run and pass? | -- | Go to Step 22 | Go to Step 2 |
22 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |
DTC P0140 or P0160 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) supplies a voltage of about 450 mV between the 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
| • | DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, 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 run time is more than 409 seconds. |
| • | The vehicle is operating in Closed Loop. |
| • | The ignition 1 signal is between 9-18 volts. |
| • | The fuel alcohol content is less than 90 percent. |
| • | Intrusive tests are not in progress. |
| • | The scan tool output controls are not active. |
Conditions for Setting the DTC
| • | The HO2S voltage is steady between 410-490 mV for 150 seconds. |
| • | The TP changes more than 5 percent within 1 second, 6 times. |
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: 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 the 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.
-
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 | No | ||||
|---|---|---|---|---|---|---|---|---|
|
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 | ||||||||
1 | Did you perform the Diagnostic System Check-Engine Controls? | -- | Go to Step 2 | |||||
|
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.
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 | |||||
Is the HO2S voltage outside the specified range? | 410-490 mV | Go to Step 4 | Go to Step 5 | |||||
4 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Intermittent Conditions | ||||
5 | Are Both DTCs P0140 and P0160 set? | -- | Go to Step 6 | Go to Step 7 | ||||
Does the test lamp illuminate? | -- | Go to Step 11 | Go to Step 10 | |||||
Is the HO2S voltage less than the specified value? | 200 mV | Go to Step 11 | Go to Step 8 | |||||
8 |
Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 9 | ||||
9 | Test for an open between terminal A of the affected sensor harness connector and one of the following PCM terminals:
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 18 | ||||
10 |
Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 18 | ||||
11 | Remove the jumper from the previous step, if applicable. Is the O2B fuse open? | -- | Go to Step 14 | Go to Step 12 | ||||
12 |
Does the test lamp illuminate? | -- | Go to Step 13 | Go to Step 19 | ||||
13 |
Does the test lamp illuminate? | -- | Go to Step 17 | Go to Step 20 | ||||
Did you find and correct a short to ground in the ignition 1 voltage circuit? | -- | Go to Step 23 | Go to Step 15 | |||||
15 |
Important: Perform the following test on HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2. 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 21 | Go to Step 16 | ||||
|
Important: Perform the following test on HO2S bank 1 sensor 2 and HO2S bank 2 sensor 2. 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 21 | Go to Intermittent Conditions | |||||
17 | 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 23 | Go to Step 21 | ||||
18 | 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 23 | Go to Step 22 | ||||
19 | 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 23 | -- | ||||
20 | Repair the open in the HO2S heater ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 23 | -- | ||||
21 | Replace the affected HO2S refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||
22 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 23 | -- | ||||
23 |
Does the DTC run and pass? | -- | Go to Step 24 | Go to Step 2 | ||||
24 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||
