For 1990-2009 cars only
DTC P0301-P0308 Federal Emissions
Circuit Description
The engine control module (ECM) monitors changes in crankshaft speed using inputs from the crankshaft position (CKP) sensor and the fuel injection control module (FICM). The ECM adjusts the fuel delivery to each cylinder in order to minimize crankshaft speed changes. This DTC will set when the ECM identifies a cylinder or cylinders requiring an excessive amount of fuel in order to maintain the correct crankshaft speed.
Conditions for Running the DTC
| • | The engine is running at idle for more than 30 seconds. |
| • | The engine coolant temperature (ECT) is more than 56°C (132°F). |
Conditions for Setting the DTC
The fuel rate adjustment for a cylinder exceeds an acceptable value.
Action Taken When the DTC Sets
| • | The control module stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records. |
| • | The driver information center (DIC), if equipped, may display a message. |
Conditions for Clearing the MIL/DTC
| • | 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 non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
Diagnostic Aids
A misfire with no other DTCs will be caused by an engine mechanical or fuel injector problem.
Step | Action | Yes | No |
|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Engine Controls? | Go to Step 2 | |
2 | Are there any other DTCs set? |
