P0152

Circuit Description

The PCM provides a 0.45 volt reference signal to the oxygen sensor on CKT 412. When the oxygen sensor is cold, below 200°C (392°F), the oxygen sensor signal voltage will be around 0.45 volt and the PCM will keep the system in Open Loop operation. When the oxygen sensor is warm, above 200°C (392°F), the oxygen sensor will swing from rich to lean rapidly, if the PCM is in good control of the air fuel mixture. DTC P0152 is designed so that if the oxygen sensor stays at a rich voltage for more than 50 seconds during the test conditions, this DTC will set. DTC P0152 will set when:

^ There is an oxygen sensor circuit fault giving a false rich indication.
^ The air fuel ratio is actually rich due to a fuel control or emission system fault.

Conditions for Running the DTC

^ DTCs P0101, P0102, P0103, P0107, P0108, P0117, P0118, P0122, P0123, P0152 and P0154 not set.
^ TP sensor between 5.4 and 25 degrees.
^ Coolant temperature 72.5°C (162.5°F) or greater.
^ Closed loop fuel control enabled.
^ Oxygen sensor ready.
^ Engine speed 800 RPM or greater.
^ MAP sensor greater than 32 kPa.
^ Above conditions met for 3 seconds.

Conditions for Setting the DTC

Oxygen sensor has been rich, 534 mV (0.534 V) or greater for 50 seconds.

Action Taken When the DTC Sets

^ PCM enables Evaporative Emission (EVAP) control solenoid if DTC P0131, P0132 or P0134 is also set.
^ Transaxle shift adapts maintained at current levels.
^ PCM disables Closed Loop and long term fuel trim operation if DTC P0131, P0132, or P0134 is also set.
^ PCM uses rear bank oxygen sensor feedback for Closed Loop and long term fuel trim operation if DTC P0131, P0132, and P0134 are not set.
^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) when the diagnostic runs and fails.
^ The PCM will record operating conditions at the time the diagnostic fails. This information will be stored in the Freeze Frame and Failure Records.

Conditions for Clearing the MIL/DTC

^ The PCM will turn the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
^ A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.
^ A History DTC will clear after forty consecutive warm-up cycles with no failures of any emission related diagnostic test.
^ Use a scan tool to clear DTCs.
^ Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended.

Diagnostic Aids

Notice: Do not solder heated oxygen sensor wires. Soldering the wires will result in the loss of the air reference to the sensor. Check snapshot data for front and rear long term fuel trim values. If both banks were rich, check for a condition that would cause rich engine operation.

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

3. If the Oxygen Sensor is operating correctly, voltage will fluctuate, below 0.6 volt. A rich sensor/condition will cause the voltage to remain above 0.6 volt.
4. Checking for proper oxygen sensor operation. The voltage should fluctuate below 0.6 volt.