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.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC P0301 Cylinder 1 Misfire Detected |
| • | DTC P0302 Cylinder 2 Misfire Detected |
| • | DTC P0303 Cylinder 3 Misfire Detected |
| • | DTC P0304 Cylinder 4 Misfire Detected |
| • | DTC P0305 Cylinder 5 Misfire Detected |
| • | DTC P0306 Cylinder 6 Misfire Detected |
| • | DTC P0307 Cylinder 7 Misfire Detected |
| • | DTC P0308 Cylinder 8 Misfire Detected |
Conditions for Running the DTC
| • | DTCs P0116, P0117, P0118, P0335, and P0336 are not set. |
| • | The engine is running at idle for more than 30 seconds. |
| • | The engine coolant temperature (ECT) is more than 56°C (132°F). |
| • | DTC P0301-P0308 will run once per ignition cycle once the above
conditions are met. |
Conditions for Setting the DTC
The fuel rate adjustment for a cylinder exceeds an acceptable value for more
than 30 seconds.
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.
