GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2007 🢒 Sierra Classic - 4WD 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0300-P0308

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0300 : Engine Misfire Detected

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

Circuit/System Description

The engine control module (ECM) monitors changes in crankshaft speed using input from the crankshaft position sensor. The 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, a DTC will set.

Conditions for Running the DTC

P0300

    • The engine is running at idle for more than 10 seconds.
    • The engine coolant temperature (ECT) is more than 40°C (104°F).
    • DTC P0300 runs once per ignition cycle when the above conditions are met .
    • DTCs P0301-P0308 must run before DTC P0300 runs.

P0301-P0308

    • DTCs P0117, P0118, P0335, P0336, P0502, P2146, P2149, P2152, P2155 and P062C are not set.
    • The ECT is more than 40°C (104°F).
    • The engine is running at idle for more than 10 seconds.
    • The engine RPM is between 500-1,500 RPM.
    • The vehicle speed is less than 3 mph.
    • The calculated fuel rate is between 3 mm³ and 25 mm³.
    • DTCs P0301-P0308 will run once per ignition cycle in a total of 440 engine revolutions when the above conditions are met.

Conditions for Setting the DTC

Cylinder RPM is less than the minimum average cylinder speed after an injection event counted 180 times.

Actions Taken When the DTC Sets

DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, and P0308 are type B DTCs.

Conditions for Clearing the MIL/DTC

DTC P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, and P0308 are type B DTCs.

Reference Information

Schematic Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Component Views

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Circuit/System Testing
  1. Unplug the fuel injector for the cylinder that indicated the misfire.
  2. Start the engine. Record the DTCs that set. The appropriate injector control circuit DTC P0201-P0208 should set.
    3. ⇒If the appropriate injector control circuit DTC did not set replace the ECM.
  3. Reconnect the injector and clear the DTCs. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.
    4. ⇒If any DTCs other than P0300-P0308 are set, diagnose those DTCs first.
    ⇒If only DTC P0300-P0308 are set, go to Fuel Injector Balance Test with Tech 2 .

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for replacement , setup, and programming