P0135

DTC P0135

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptors
DTC P0135
- HO2S Heater Performance Sensor 1




Diagnostic Fault Information






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.


Conditions for Running the DTCs


Conditions 1
* Before the ECM can report DTC P0135 failed, DTCs P0030, P0031, P0032, P0101, P0102, P0103, P0121, P0122, P0123, P0130, P0131, P0132, P0221, P0222, P0223, P0335, P0336, P0338, P167A, P2237, P2243, and P2251 must run and pass.
* The ignition 1 voltage is between 11-18 volts.
* The HO2S is at operating temperature for greater than 50 seconds.
* The time after decel fuel cut-off is greater than 50 seconds.
* The HO2S heater is commanded ON to 100 percent.
* The calculated exhaust temperature is greater than 400°C (752°F).
* The ECM internal sensing element resistance test is enabled.
* DTC P0135 runs continuously once the above conditions are met for 1 minute.



Conditions 2
* Before the ECM can report DTC P0135 failed, DTCs P0030, P0031, P0032, P0101, P0102, P0103, P0121, P0122, P0123, P0130, P0131, P0132, P0221, P0222, P0223, P0335, P0336, P0338, P167A, P2237, P2243, and P2251 must run and pass.
* The ignition 1 voltage is between 11-18 volts.
* The ECT is greater than -10°C (+14°F) at start up.
* The HO2S is at operating temperature.
* The ECM internal sensing element resistance test is enabled.
* The fuel injectors are not disabled.
* If the engine is operating and then the ignition is turned OFF, the engine must be OFF for at least 5 minutes before the next start-up for the diagnostic to run.
* DTC P0135 runs continuously once the above conditions are met for greater than 2 minutes.



Conditions for Setting the DTCs


Conditions 1
* The ECM has determined that the HO2S internal sensing element resistance is less than a predetermined threshold.
* The above condition is exists for greater than 4 seconds.



Conditions 2
* The ECM detects that the calculated HO2S temperature is less than 600°C (1,112°F).
* The above condition is exists for greater than 4 seconds.



Action Taken when the DTCs Set

DTC P0135 is a Type B DTC.


Conditions for Clearing the MIL/DTCs

DTC P0135 is a Type B DTC.


Diagnostic Aids

The following table illustrates the ECM connector locations:





* The front wide band sensor does not toggle or switch like a switching HO2S. The front HO2S signal will be relatively stable for an idling engine.
* The following table illustrates the typical voltages for the HO2S circuits:







Reference Information
Schematic Reference

Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Engine idling at normal operating temperature, observe the scan tool HO2S 1 Loop Status parameter. The parameter should display Closed Loop.
2. 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

1. Ignition OFF, disconnect the harness connector at the HO2S 1.
2. Ignition ON, load test for B+ between the ignition voltage circuit terminal 3 and ground.

• If less than the specified range, repair the ignition voltage circuit for a short to ground, or an open/high resistance.

3. Test for 4.6-5 volts between the heater control circuit terminal 4 and ground.

• If less than the specified range, test the heater control circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.

4. Ignition ON, test for 2.5-3.5 volts between the high signal circuit terminal 1 and ground.

• If less than the specified range, test the high signal circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the ECM.


• If greater than the specified range, test the high signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. Test for 2-3 volts between the low signal circuit terminal 5 and ground

• If less than the specified range, test the low signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.


• If greater than the specified range, test the low signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

6. If all conditions test normal, replace the HO2S 1.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Heated Oxygen Sensor 1 Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for engine control module replacement, setup, and programming