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 P0135: HO2S Heater Performance Sensor 1DTC P0141: HO2S Heater Performance Sensor 2
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Ignition 1 Voltage | P0135, P0141 | P0135, P0141 | -- | -- |
HO2S 1 Heater Control | P0135 | P0135 | P0135 | -- |
HO2S 2 Heater Control | P0141 | P0141 | P0141 | -- |
Circuit Description
The heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content in the exhaust stream. The HO2S must reach operating temperature to provide an accurate voltage signal. A heating element inside the HO2S minimizes the time required for the sensor to reach operating temperature. Voltage is provided to the heater by the ignition 1 voltage circuit through a fuse. Ground is provided to the heater on the low control circuit by a low side driver within the control module. The control module monitors the current draw of the heater to determine if a failure is present.
The HO2S utilizes the following circuits:
| • | A signal circuit |
| • | A low reference circuit |
| • | An ignition 1 voltage circuit |
| • | A heater control circuit |
Conditions for Running the DTC
P0135
| • | DTCs P0106, P0107, P0108, P0117, and P0118 are not set. |
| • | The system voltage is greater than 10 volts. |
| • | The engine has been operating more than 60 seconds. |
| • | The DTCs run continuously when the above conditions are met for 12 seconds. |
P0141
| • | The engine has been operating for 60 seconds. |
| • | The system voltage is greater than 10 volts. |
| • | The DTCs run continuously when the above conditions are met for 12 seconds. |
Conditions for Setting the DTC
The ECM detects that the HO2S heater current is less than 0.1 amp.
Action Taken When the DTC Sets
DTC P0135 and P0141 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTC P0135 and P0141 are Type B DTCs.
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Circuit/System Verification
Important: It may take up to 8 minutes for the DTC to set.
With the engine at normal operating temperature, operate the engine above 1,200 RPM for 30 seconds, then allow the engine to idle. DTC P0135 or P0141 should not set.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate H02S.
- Ignition ON, verify that a test lamp illuminates between the ignition 1 voltage circuit and ground.
- Ignition OFF, connect a test lamp between the control circuit and B+. The test lamp should not illuminate.
- Start and idle the engine, and verify the test lamp illuminates or flashes.
- If all circuits/connections test normal, test or replace the H02S sensor.
Important: The ignition 1 voltage circuit supplies voltage to other components. Make sure you test all circuits for a short to ground or test all components for being shorted that share the ignition 1 voltage circuit.
| ⇒ | If the test lamp does not illuminate, test the ignition 1 voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition 1 voltage circuit fuse is open, test all components connected to the ignition 1 voltage circuit and replace as necessary. |
| ⇒ | If test lamp is always ON, test the control circuit for a short to ground. If the circuit/connections test normal, replace the ECM. |
| ⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit/connections test normal, replace the ECM. |
Component Testing
- Ignition OFF, disconnect the harness connector of the HO2S.
- Test the HO2S heater resistance for 3-35 ohms.
| ⇒ | If the resistance is out of the specified range, replace the HO2S. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for engine control module replacement, setup, and programming
