P0300

DTC P0300

CIRCUIT DESCRIPTION
The engine control module (ECM) monitors changes in crankshaft speed using inputs from the crankshaft position (CKP) sensor. The ECM adjusts the fuel delivery amount 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, it is considered a misfire and DTC P0301 - P0304 will set depending upon which cylinder failed. If it occurred in more than one cylinder, this DTC will set.

Condition for Running the DTC
- DTCs P0016, P0089, P0091, P0092, P0093, P0112, P0113, P0116, P0117, P0118, P0192, P0193, P0201, P0202, P0203, P0204, P0261, P0264, P0267, P0270, P0335, P0336, P0500, P0506, P0507, P0602, P0642, P0643, P1093, P1125, P1293, P2146, P2147, P2148, P2149, P2150, P2151, P2227, P2228 and P2229 are not set.
- The battery voltage is between 10-16 volts.

Condition for Setting the DTC
- The ECM detects that the misfire has occurred in more than one cylinder for longer than 70 seconds.

Action Taken When the DTC Sets
- The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
- The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Freeze Frame/Failure Records.
- The ECM closes the EGR valve and holds to close position.

Condition for Clearing the MIL/DTC
- The ECM turns OFF the MIL after 3 consecutive driving cycles when 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 after the ECM turns OFF the MIL.
- Clear the MIL and the DTC with a scan tool.

Diagnostic Aids
- An engine mechanical or fuel injector problem will cause this DTC to set.
- Use a scan tool to observe the "Balancing Rate" for each cylinder at idle. A cylinder that is excessively large or small balancing rate may indicate incorrect fuel injector flow rate, faulty fuel injectors, and weak or slightly seized cylinder.
- DTC P0300 should always be set with a P0301-P0304.
- If multiple cylinder are misfiring, problem in the fuel system, low fuel level or contaminated fuel may exist.