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VIN L




DTC P0300-P0308

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (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 Misfire DTC will set.

Conditions for Running the DTC

* DTCs P0117, and P0118 are not set.
* The Crankshaft Position Reluctor Wheel Learn procedure has successfully completed.
* The ECT is warmer than 40°C (104°F).
* The engine is running at idle for more than 10 s.
* The engine RPM is between 400-1,300 RPM.
* The vehicle speed is less than 2 mph.
* The calculated fuel rate is between 5 mm(3) and 100 mm(3).
* The fuel level is above 15%.
* DTCs P0300-P0308 will run once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

The ECM is detecting a crankshaft rotation speed change indicating a misfire sufficient to cause emission levels to exceed mandated standards.

Actions Taken When the DTC Sets

DTCs P0300-P0308 are Type B DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0300-P0308 are Type B DTCs.

Diagnostic Aids

* A misfire may occur only when the engine is operating under a load.
* The Crankshaft Position Reluctor Wheel Learn procedure may need to be performed.
* Contaminated or improper fuel quality may cause this DTC to set.
* A misfire DTC could be caused by an excessive vibration from sources other than the engine. Inspect the following for possible sources of vibration:

- A damaged accessory drive component or belt; remove the belt and safely operate the engine to evaluate
- A damaged reluctor wheel

Reference Information
Schematic Reference

Engine Controls Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Verify that the fuel used is proper. Refer to Fuel System Specifications (Fuel System Specifications) and Contaminants-in-Fuel Diagnosis (Contaminants-in-Fuel Diagnosis)
2. Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition ON, observe the DTC information with a scan tool.

If a DTC, other than P0300-P0308, P0263, P0266, P0269, P0272, P0275, P0278, P0281, P0284, or P12B3-P12C1 is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code (DTC) List - Vehicle).

2. With a scan tool, perform the Cylinder Compression Test.

If the compression test results are erratic, refer to Engine Compression Test (Testing and Inspection).

3. Perform the Crankshaft Position Reluctor Wheel Learn procedure. Refer to, Crankshaft Position Reluctor Wheel Learn (Testing and Inspection).
4. Operate the vehicle within the Conditions for Running the DTC to verify that the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
5. Ignition ON, observe the DTC information with a scan tool.

If DTC P0301-P0308 is set, replace the injector for the cylinder with the Misfire DTC. Refer to Fuel Injector Replacement (Left Side) (Fuel Injector Replacement (Left Side)) Fuel Injector Replacement (Right Side) (Fuel Injector Replacement (Right Side)).

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.

Control Module References (Programming and Relearning) for ECM replacement, setup, and programming.