DTC P0137 or P0157 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 for being fixed below a predetermined voltage. If the PCM detects the voltage is below a predetermined voltage, 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 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. |
Lean Test Enable:
| • | The air fuel ratio is between 14.5:1-14.7:1. |
| • | For vehicles with throttle-actuated control (TAC), the throttle position (TP) indicated angle is between 3-70 percent more than the value observed at idle. |
| • | For vehicles without TAC, the TP is between 3-70 percent. |
Power Enrichment Test Enable:
| • | Power enrichment is active. |
| • | The above condition is met for 2 second. |
Conditions for Setting the DTC
Lean Test
The HO2S voltage is less than 80 mV for 400 seconds.
Power Enrichment Test
The HO2S voltage is less than 420 mV for 10 seconds.
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.
| • | HO2S wire--Sensor pigtail may be in contact with the exhaust manifold or the exhaust system. |
| • | 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. |
| • | Inspect for intermittent ground in the signal wire between the connector and the sensor. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | Lean injectors--Perform the Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 or Fuel Injector Balance Test with Special Tool . |
| • | Fuel contamination--Water near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can set a DTC. Refer to Alcohol/Contaminants-in-Fuel Diagnosis . |
| • | Fuel pressure--System will be lean if fuel pressure is low. Refer to Fuel System Diagnosis . |
| • | Exhaust leaks--An exhaust leak near the HO2S can cause a lean condition. Refer to Exhaust Leakage in Engine Exhaust. |
| • | Vacuum or crankcase leaks can cause a lean condition. |
| • | If the above are OK, the HO2S may be at fault. |
For an intermittent condition, refer to Intermittent Conditions .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
If the voltage is below the specified value the condition is present.
-
Jumpering the HO2S low signal circuit to ground is necessary for the PCM to correctly measure the voltage on the HO2S high signal circuit. If the HO2S voltage is within the specified range, the PCM and HO2S high signal circuit are OK.
Step | Action | Value(s) | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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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: With the engine running, observe the front HO2S voltage using a scan tool. If the front HO2S voltage is fixed above 900 mV, refer to DTC P0132 or P0152 .
Is the HO2S voltage less than the specified value? | 80 mV | Go to Step 5 | Go to Step 3 | |||||||||||||
3 |
Is the HO2S voltage within the specified range? | 350-550mV | Go to DTC P0140 or P0160 | Go to Step 4 | ||||||||||||
4 |
Does the DTC fail this ignition? | -- | Go to Step 5 | Go to Diagnostic Aids | ||||||||||||
Is the HO2S voltage within the specified range? | 350-550 mV | Go to Step 6 | Go to Step 7 | |||||||||||||
6 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 9 | ||||||||||||
7 |
Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 8 | ||||||||||||
8 | Test the HO2S high signal circuit for a short to the HO2S Low signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 13 | Go to Step 10 | ||||||||||||
9 | Inspect for poor connections at the harness connector of the 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 13 | Go to Step 11 | ||||||||||||
10 | 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 13 | Go to Step 12 | ||||||||||||
11 | 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 13 | -- | ||||||||||||
12 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 13 | -- | ||||||||||||
13 |
Does the DTC run and pass? | -- | Go to Step 14 | Go to Step 2 | ||||||||||||
14 | 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 P0137 or P0157 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 for being fixed below a predetermined voltage. If the PCM detects the voltage is below a predetermined voltage, 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 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. |
Lean Test Enable:
| • | The air fuel ratio is between 14.5:1-14.7:1. |
| • | For vehicles with throttle-actuated control (TAC), the throttle position (TP) indicated angle is between 3-70 percent more than the value observed at idle. |
| • | For vehicles without TAC, the TP is between 3-70 percent. |
Power Enrichment Test Enable:
| • | Power enrichment is active. |
| • | The above condition is met for 2 second. |
Conditions for Setting the DTC
Lean Test
The HO2S voltage is less than 80 mV for 400 seconds.
Power Enrichment Test
The HO2S voltage is less than 420 mV for 10 seconds.
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 repair, refer to Wiring Repairs or Connector Repairs in Wiring Systems.
Inspect for the following conditions:
| • | A sensor pigtail may be mispositioned and contacting the exhaust system. |
| • | An intermittent short to ground in the signal circuit between the PCM connector and HO2S |
| • | A poor PCM to the engine block ground |
| • | Lean injectors--Perform the Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 . |
| • | Fuel contamination--Water, even in small amounts, near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can also set this DTC. Refer to Alcohol/Contaminants-in-Fuel Diagnosis . |
| • | Fuel pressure--If the pressure is too low, the system will be lean. In order to confirm, monitor a fuel pressure while driving the vehicle at various speeds and loads. Refer to Fuel System Diagnosis . |
| • | Exhaust leaks--If there is an exhaust leak, the engine may pull the outside air into the exhaust and past the sensor. Refer to Exhaust Leakage in Engine Exhaust. |
| • | Vacuum or crankcase leaks can cause a lean condition or possibly a high idle. |
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 number below refers to the step number on the diagnostic table.
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 | |||||||||||||||||||||
2 |
Is the HO2S voltage fixed less than the value specified? | 80 mV | Go to Step 5 | Go to Step 3 | ||||||||||||||||||||
3 |
Is the HO2S voltage within the specified range? | 350-550mV | Go to DTC P0140 or P0160 | Go to Step 4 | ||||||||||||||||||||
4 | The condition that set this DTC is not present. This DTC may have been set by one of the following conditions:
Repair any of the above or similar engine conditions as necessary. Did you find and correct the condition? | -- | Go to Step 11 | Go to Diagnostic Aids | ||||||||||||||||||||
5 |
Is the HO2S voltage within the specified value range? | 351-551 mV | Go to Step 6 | Go to Step 7 | ||||||||||||||||||||
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 | |||||||||||||||||||||
7 |
Is the resistance at the specified value on both tests? | ∞ | Go to Step 10 | Go to Step 8 | ||||||||||||||||||||
8 | Repair the HO2S signal high circuit shorted to ground or shorted to the HO2S low circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Step 11 | -- | ||||||||||||||||||||
9 | Replace the HO2S. Refer to Heated Oxygen Sensor Replacement - Bank 1 Sensor 2 or refer to Heated Oxygen Sensor Replacement - Bank 2 Sensor 2 . Did you complete the replacement? | -- | Go to Step 11 | -- | ||||||||||||||||||||
10 | Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- | ||||||||||||||||||||
11 |
Does the DTC run and pass? | -- | Go to Step 12 | Go to Step 2 | ||||||||||||||||||||
12 | With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK | |||||||||||||||||||||
