P0301

P0301-CYLINDER 1 MISFIRE

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Crankshaft Position (CKP) and Camshaft Position (CMP) Sensors are hall effect type sensors. The Powertrain Control Module (PCM) provides a 5-Volt supply to the position sensor and return circuit. A notch on the crankshaft gear is used to determine the position of the engine by the PCM. As the notch on the crankshaft speed ring or the windows in the back of the camshaft gear move past the position sensor, a signal is generated on the position sensor circuit. The change in engine speed when different calibrated fuel quantities are added by the injector to this cylinder is a measure of how well the cylinder is firing. This DTC is a two trip fault. Active regeneration will be disabled when the mill lamp is on. The PCM will turn off the MIL lamp after the monitor runs and passes three consecutive times.

- When Monitored:
While the engine is idling at operating temperature.

- Set Condition:
Misfire detected on this cylinder.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. LOW FUEL
1. Using the scan tool, verify that the fuel level is above 15%.

Is the fuel level above 15%?

Yes

- Go To 2

No

- Add fuel.
- Go To 2

2. OTHER DTCs
1. Read the Freeze frame data.

Is the DTC equal to the freeze frame DTC?

Yes

- Go To 3

No

- Repair any other DTCs first.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

3. CHECK FOR DAMAGED FUEL LINES
1. Visually inspect the injector supply line for damage.

Do you have any kinked or bent fuel lines?

Yes

- Repair or replace the damaged fuel line.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. CHECK THE VALVE TRAIN
1. Visually inspect the valve train and check the valve lash on the suspect cylinder.

Is the valve train functional and the lash within the specifications listed in the service manual?

Yes

- Go To 5

No

- Adjust the lash or fix or repair any damaged components.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

5. CHECK FOR OBSTRUCTED FUEL INJECTOR SUPPLY
1. Remove the fuel injector supply line for the suspect cylinder.
2. Inspect both ends of the fuel injector supply line for damage.
3. Using shop air pressure, blow out the fuel injector supply line to verify that they are not obstructed.

Are the fuel lines free of debris or damage?

Yes

- Go To 6

No

- Replace the damaged or obstructed fuel injector supply line.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. CHECK FOR DAMAGED OR OBSTRUCTED HIGH PRESSURE CONNECTOR
1. Remove the high pressure connector for the suspect cylinder.
2. Inspect both ends of the high pressure connector for signs of damage.
3. Using shop air pressure, blow out the high pressure connector to verify that it is not obstructed.

Are the high pressure connectors free of debris or damage?

Yes

- Go To 7

No

- Replace the damaged or obstructed high pressure connector.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

7. CHECK THE FUEL INJECTOR
1. Remove the suspect fuel injector.

Is the fuel injector damaged?

Yes

- Replace the external damaged fuel injector and high pressure connector.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 8

8. INTERNAL DAMAGED FUEL INJECTOR
1. With the scan tool, erase DTCs.
2. Switch the misfiring injector and high pressure connector with an injector and high pressure connector from a cylinder that is firing properly.
3. Operate the vehicle.

Did the misfire DTC follow the suspect injectors and high pressure connectors?

Yes

- Replace the internal damaged fuel injector and high pressure connector.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 9

9. CHECK FOR INTERNAL ENGINE DAMAGE
1. Perform engine compression test.

Did the suspect cylinder pass the compression test?

Yes

- Go To 10

No

- Repair the internal damage to the engine.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

10. CHECK FOR INTERNAL ENGINE DAMAGE
1. Perform engine leak down test.

Did the suspect cylinder pass the leak down test?

Yes

- Test Complete.

No

- Repair the internal damage to the engine.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.