Federal Emissions

DTC P0300

CIRCUIT DESCRIPTION
The engine control module (ECM) adjusts the fuel delivery to each cylinder in order to minimize crankshaft speed changes. If the ECM identifies a cylinder or cylinders requiring an excessive amount of fuel in order to maintain the correct crankshaft speed, DTC P0300 will set.

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 more than one 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.

TEST

Steps 1-2: