Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
DTC Descriptors
DTC P0141: HO2S Heater Performance Sensor 2Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
HO2S 2 Heater Control | P0137 | P0036, P0141 | P0138 | -- |
HO2S 2 Heater Supply Voltage | P0137 | P0036, P0141 | -- | -- |
Circuit Description
The heated oxygen sensor (HO2S) heater reduces the time required for the oxygen sensor (O2S) to reach operating temperature and maintains the operating temperature during extended idle periods. When the ignition is turned to the ON position, ignition voltage is supplied directly to the sensor heater. The engine control module (ECM) controls the heater operation by first modulating the control circuit to ground when the sensors are cold. This prevents the possibility of thermal shock to the sensor, from condensation build-up on the sensor, by controlling the sensors rate of heating. After a predetermined amount of time, the ECM commands the heaters ON continuously. Once the sensor reaches operating temperature, the ECM may modulate the heater control circuit to ground, to maintain a desired temperature.
The ECM controls the heater by grounding the control circuit with a solid state device called a driver. The driver is equipped with a feedback circuit that is pulled-up to voltage. The ECM can determine if the control circuit is open, shorted to ground, or shorted to a voltage by monitoring the feedback voltage.
Conditions for Running the DTCs
| • | Before the ECM can report DTC P0141 failed, DTCs P0036, P0037, and P0038 must run and pass. |
| • | DTCs P0137, P0138, P0140, P2232, P2270, and P2271 are not set. |
| • | The engine is operating. |
| • | The ignition voltage is between 11-18 volts. |
| • | The ECM internal sensing element resistance test is valid. |
| • | The fuel system is not in a decel fuel shut-off. |
| • | The intake air temperature (IAT) is greater than -30°C (-22°F). |
| • | If the engine is operating and then the ignition is turned OFF, the engine must be OFF for at least 2 minutes before the next start-up for the diagnostic to run. |
| • | The calculated exhaust temperature is between 360-500°C (680-932°F). |
| • | DTC P0141 runs continuously once the above conditions are met for greater than 100 seconds. |
Conditions for Setting the DTCs
| • | The ECM detects that the HO2S 2 internal resistance is not within the expected range. |
| • | The above condition is exists for greater than 4 seconds, or for a cumulative of 50 seconds. |
Action Taken when the DTCs Set
DTC P0141 is a Type B DTC.
Conditions for Clearing the MIL/DTCs
DTC P0141 is a Type B DTC.
Diagnostic Aids
The following table illustrates the ECM connector locations:
ECM Connector Location | |
|---|---|
X2 | X1 |
Front of Vehicle | |
The rear HO2S will not go into closed loop when the engine is idling. Once the HO2S are at operating temperature, and the vehicle is moving, the rear HO2S will go into closed loop.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Engine idling at normal operating temperature, observe the scan tool DTC information. DTC P0141 should not set.
- Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the HO2S 2.
- Ignition ON, load test for B+ between the ignition voltage circuit terminal E and ground.
- Connect a 3A fused jumper wire between the high signal circuit terminal B and ground. Verify the scan tool HO2S 2 voltage parameter is less than 10 mV.
- Connect a 3A fused jumper wire between the high signal circuit terminal B and the low signal circuit terminal A. Verify the scan tool HO2S 2 voltage parameter is less than 10 mV.
- Test for less than 5 ohms of resistance between the heater control circuit terminal D and the ECM.
- If all conditions test normal, replace the HO2S 2.
| ⇒ | If less than the specified range, repair the ignition voltage circuit for a short to ground, or an open/high resistance. |
| ⇒ | If greater than the specified range, repair the high signal circuit for an open/high resistance. |
| ⇒ | If greater than the specified range, test the low signal circuit for an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If greater than the specified range, repair the heater control circuit for an open/high resistance. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for engine control module replacement, setup, and programming |
