For 1990-2009 cars

The heated oxygen sensor 2 (H02S- 2) is located behind the catalytic converter. The sensor is used by the PCM to determine the oxygen storage capability of the catalytic converter. Due to the location of the HO2S-2, a heater element is required to provide additional heat, which speeds up sensor activation time. The heater is supplied ignition voltage whenever the ignition is turned ON. The PCM will monitor the time it takes for the sensor to become active which can determine if the heater is working properly. DTC P0141 sets when the HO2S-2 is not fluctuating outside a voltage window that is centered around bias voltage after the engine has been running a certain length of time. This indicates the sensor heater is not working properly.

### Conditions for Setting the DTC

DTC P0141 will set if HO2S-2 is inactive, voltage is not fluctuating outside 295-591 mV range, for too long when:

• | The engine run time is less than 4 minutes and 15 seconds.

• | The startup ECT and IAT are less than 45°C (113°F).

• | The ECT and IAT are within 7°C (45°F) of each other.

• | Ignition voltage is between 11.6-16 volts.

• | The O2S-1 at engine startup was between 395-491 mV.

• | The calculated average airflow prior to H2OS-2 activity was less than 20 g/s.

• | No CKP, ECT, EVAP, fuel injector, fuel tank pressure, fuel trim, IAT, idle speed, MAP, misfire, PCM internal fault, or TP sensor DTCs have been set.

DTC P0141 diagnostic runs once per ignition cycle once the above conditions have been met.

DTC P0141 is a type B DTC.

### Diagnostic Aids

Heater element resistance is 5-7.8 ohms.