P0054
DTC P0054
CIRCUIT DESCRIPTION
Heated oxygen sensors (HO2S) are used for fuel control and post catalyst monitoring. Each HO2S compares the oxygen content of the surrounding air with the oxygen content of the exhaust stream. When the vehicle is first started, the powertrain control module (PCM) operates in an Open Loop mode, ignoring the HO2S signal voltage when calculating the air-to-fuel ratio. The PCM supplies the HO2S with a reference, or bias, voltage of about 450 mV. The HO2S generates a voltage within a range of 0-1,000 mV that fluctuates above and below bias voltage once the sensor reaches operating temperature. A high HO2S voltage output indicates a rich fuel mixture. A low HO2S voltage output indicates a lean mixture. Heating elements inside the HO2S minimize the time required for the sensors to reach operating temperature and to provide an accurate voltage signal. The PCM controls the HO2S 2 heater low control circuit with a low side driver. The PCM commands the heater ON or OFF to maintain a specific HO2S operating temperature range. The PCM determines the temperature by measuring the current flow through the heater. When the heater is in the ON state, the PCM will pulse the heater OFF for a duration of 50 ms per second. When the heater is in the OFF state, the PCM will pulse the heater ON for a duration of 50 ms once per second. If the PCM detects that the HO2S 2 heater low control circuit current level is not within the calibrated range, DTC P0054 will set for bank 1 sensor 2.
The HO2S 2 has the following circuits:
- The HO2S 2 high signal circuit
- The HO2S 2 low reference circuit
- The HO2S 2 ignition 1 voltage circuit
- The HO2S 2 heater low control circuit
DTC DESCRIPTOR
This diagnostic procedure supports the following DTC:
DTC P0054 HO2S Heater Resistance Bank 1 Sensor 2
CONDITIONS FOR RUNNING THE DTC
- The ignition is OFF for more than 10 hours.
- The ECT Sensor parameter minus the IAT Sensor parameter is less than 8°C (14°F) at engine start-up.
- The ECT Sensor parameter is between -30 and +45°C (-22 and +133°F) at engine start-up.
- The system voltage is between 9-18 volts.
- This diagnostic runs once per valid cold start when the above conditions are met.
CONDITIONS FOR SETTING THE DTC
The PCM detects that the HO2S 2 heater calculated resistance is not within an expected range at engine start-up for 1 second.
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.
TEST
