P0135

DTC P0135, P0141, P0155, or P0161

Circuit Description

Heating elements inside the heated oxygen sensor (HO2S) minimize the time required for the sensors to reach operating temperature, and to provide an accurate voltage signal. A low side driver within the engine control module (ECM) is pulse-width controlled to provide current to the heater elements. During warm-up, the ECM will reduce the ON time to prevent thermal shock to the sensor components from moisture in the exhaust system. The ECM will not allow full HO2S heating until calibrated limits of time, temperature, and intake airflow have been reached. The ECM periodically monitors the HO2S operating state by briefly turning OFF the heater low side driver at regular intervals. A small reference voltage of approximately 3.6 volts is present at the heater low control circuit. When the low side driver is commanded ON, the reference voltage is low. When the low side driver is commanded OFF, the reference voltage is high, close to battery voltage. The ECM calculates the HO2S element resistance based on the HO2S heater command voltage and calculated exhaust gas temperature. If the ECM detects that the HO2S heater element resistance is too high, the following DTCs will set:

- DTC P0135 for HO2S bank 1 sensor 1
- DTC P0141 for HO2S bank 1 sensor 2
- DTC P0155 for HO2S bank 2 sensor 1
- DTC P0161 for HO2S bank 2 sensor 2

Conditions for Running the DTC

- DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0056, P0057, P0058, P0157, P0158, P0160, P0161 are not set.
- The Engine Run Time parameter is more than 40 seconds.
- The calculated converter temperature is between 350°-585°C (662°-1085°F).
- The Ignition 1 voltage parameter is between 10.5-18 volts.

Conditions for Setting the DTC

The ECM detects that the affected HO2S calculated resistance is more than 680-5440 ohms for a corresponding calculated exhaust gas temperature.

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.