Advanced Diagnostics

DTC P0135: Rear Air/Fuel Ratio (A/F) Sensor (Bank 1, Sensor 1) Heater Circuit Malfunction




General Description
The rear air/fuel ratio (A/F) sensor (bank 1, sensor 1) is installed in the exhaust manifold, and it detects oxygen content in the exhaust gas. The rear A/F sensor outputs voltage to the engine control module (ECM)/powertrain control module (PCM). The ECM/PCM controls fuel injection time by comparing the target air/fuel ratio with the rear A/F sensor signal. The sensor includes the VS cell, the pump cell, the atmospheric reference cavity, the diffusion layer, and the heater, and it enables overall feedback control. The heater is controlled by the ECM/PCM and is energized when the sensor element temperature is low. It heats the sensor to stabilize the detection of oxygen content. The ECM/PCM monitors the rear A/F sensor heater output (return check). A malfunction is detected if the return signals do not meet the command value (for heater activation) in the ECM/PCM for a set time, and a DTC is stored.




Monitor Execution, Sequence, Duration, DTC Type, OBD Status




Enable Conditions

Malfunction Threshold
One of these conditions must be met for at least 2 seconds.
- No return signal "HIGH" is detected when the ECM/PCM output duty is less than 20 %.
- Return signal does not change when the ECM/PCM output duty is more than 20 % and less than 80 %.
- No return signal "LOW" is detected when the ECM/PCM output duty is more than 80 %.

Driving Pattern
Start the engine. Hold the engine speed at 3,000 rpm without load (in Park or neutral) until the radiator fan comes on, then let it idle.

Diagnosis Details

Conditions for illuminating the MIL
When a malfunction is detected, the MIL comes on and the DTC and the freeze frame data are stored in the ECM/PCM memory.

Conditions for clearing the MIL
The MIL will be cleared if the malfunction does not recur during three consecutive trips in which the diagnostic runs.

The MIL, the DTC, and the freeze frame data can be cleared by using the scan tool Clear command or by disconnecting the battery.