P0154

CIRCUIT DESCRIPTION

Engine Control Schematics: Heated Oxygen Sensors (HO2S):

The HO2S is a sensor used to detect oxygen-content in the exhaust. The PCM supplies the sensor with a signal circuit and a ground circuit. The PCM supplies a bias voltage between the circuits. The sensor varies the voltage based on the oxygen content in the exhaust. When the exhaust stream is lean (more oxygen), the sensor produces a low voltage signal. When the exhaust stream is rich (less oxygen), the sensor produces a high voltage signal.

The PCM monitors the HO2S signal during closed loop. To correct for rich or lean conditions, the PCM adjusts the injector pulse width. If HO2S bank 2 sensor 1 remains at or near the bias voltage for a calibrated period of time, DTC P0154 will set.

CONDITIONS FOR RUNNING THE DTC
^ No TP sensor, MAF sensor, MAP sensor, IAT sensor, ECT sensor, HO2S heater, EVAP system, AIR system, fuel injector, fuel trim, EGR system, Catalyst system, or system voltage DTCs are set.
^ System voltage is between 8 and 18 volts
^ Engine is running

CONDITIONS FOR SETTING THE DTC
HO2S bank 2 sensor 1 signal voltage remain within 300 and 500 mV for approximately 80 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test runs and fails.
^ The PCM stores the conditions present when the DTC set as Freeze Frame and Fail Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn the MIL OFF after the third consecutive trip in which the diagnostic runs and passes.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using the scan tool Clear DTC Information function.

DIAGNOSTIC AIDS

NOTE
^ Refer to HO2S wire repair notice in Service Precautions.
^ Refer to Connector Test Adapter Kit J35616-A Notice in Service Precautions.

For intermittent conditions, refer to Symptoms.

TEST DESCRIPTION

Steps 1 - 3:

Steps 4 - 10:

The numbers below refer to the step numbers on the diagnostic table.
5. Check the HO2S bank 2 sensor 1 wiring, the PCMs response. With the harness connector terminals jumpered together, the scan tool should display an HO2S bank 2 sensor 1 voltage below 150 mV.
9. This vehicle is equipped with a PCM which utilizes an electrically erasable programmable read only memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.