Cruze

DTC P0300-P0304

The engine control module (ECM) uses information from the crankshaft position sensor in order to determine when an engine misfire is occurring and uses information from the camshaft position sensor - inlet and camshaft position sensor - exhaust sensors in order to determine which cylinder is misfiring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect individual misfire events. If the ECM detects a misfire rate sufficient to cause emission levels to exceed mandated standards, DTC P0300 00 sets. Under certain driving conditions, a misfire rate can be high enough to cause the 3-way catalyst to overheat, possibly damaging the converter. The malfunction indicator lamp (MIL) will flash ON and OFF when converter overheating, damaging conditions are present and DTC P0300 00 is set. DTCs P0301 00 - P0304 00 correspond to cylinders 1-4. If the ECM is able to determine that a specific cylinder that is misfiring, the DTC for that cylinder will set.

The ECM is detecting a crankshaft rotation speed variation indicating a misfire sufficient to cause emission or catalyst damaging levels to exceed mandated standards.

DTCs P0300 00, P0301 00, P0302 00, P0303 00 and P0304 00 are Type A (MIL flashing) or Type B DTCs.

DTCs P0300 00, P0301 00, P0302 00, P0303 00 and P0304 00 are Type A (MIL flashing) or Type B DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Fuel System Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

For equivalent regional tools, refer to Special Tools .

1. Engine running at the normal operating temperature, verify there is no abnormal engine noise.

⇒	If there is an abnormal engine noise, refer to Symptoms - Engine Mechanical .

2. Observe the DTC information with a scan tool. Verify that DTC P0201 00, P0202 00, P0203 00, P0204 00, P0315 00, P0335 00, P0336 00, P0351 00, P0352 00, P0353 00, or P0354 00 are not set.

⇒	If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle .

Note: A misfire may only occur when the engine is under a load. An engine load may be necessary to verify the condition.

3. Observe the scan tool Misfire Current Counter parameters. The Misfire Current Counters should not be incrementing.
4. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

1. Verify that the following conditions do not exist:

•	Vacuum hose splits, kinks, and incorrect connections

•	Engine vacuum leaks

•	Crankcase ventilation system for vacuum leaks

•	Fuel pressure that is too low or too high, refer to Fuel System Diagnosis .

•	Contaminated fuel, refer to Alcohol/Contaminants-in-Fuel Diagnosis .

•	Restricted exhaust system, refer to Restricted Exhaust .

⇒	If you find any of the above conditions, repair as necessary.

2. Ignition OFF, disconnect the harness connector at the appropriate Q17 Fuel Injector.
3. Connect a test lamp between the control circuit terminal 2 and the ignition voltage circuit terminal 1.
4. Engine idling, the test lamp should flash.

⇒	If the test lamp does not flash, refer to DTC P0201, P0202, P0203, or P0204 .

5. Ignition OFF, connect the Q17 Fuel Injector connector. Remove the T8 Ignition Coil.
6. Inspect the ignition coil spark plug boots for the following conditions:

•

Damage

•	Carbon tracking

•	Oil contamination

•	Water intrusion

⇒	If you find any of the above conditions, repair as necessary.

7. Connect the harness connector to the ignition coil assembly.

Note: It may be necessary to secure the EN 36012-A Ignition System Diagnostic Harness to the spark plug boots with electrical tape.

8. Install the EN 36012-A Ignition System Diagnostic Harness to the spark plug boots.
9. Install the EL 26792 HEI Spark Tester between the spark plug boot of the misfiring cylinder and ground.
10. Connect the remaining wires to the appropriate cylinders.

Note: An erratic or weak spark is considered a no spark condition.

11. Attempt to start the engine and observe the EL 26792 HEI Spark Tester. The spark tester should spark.

⇒	If there is no spark, refer to Electronic Ignition System Diagnosis .

12. Ignition OFF, remove the spark plug from the misfiring cylinder. Verify the following conditions do not exist with the spark plug:

•	Gas, coolant, or oil fouled, refer to Spark Plug Inspection .

•	Cracked, worn, incorrectly gapped

⇒	If there is a condition with the spark plug, replace the spark plug.

13. Exchange the suspected spark plug with another cylinder that is operating correctly.
14. Engine running, observe the scan tool Misfire Current Counters. The misfire should not follow the spark plug exchange.

⇒	If the misfire follows the spark plug, replace the spark plug.

15. If all conditions test normal, test or inspect for the following:

•	A lean or rich fuel injector, refer to Fuel Injector Diagnosis .

•	An engine mechanical condition, refer to Symptoms - Engine Mechanical .

1. If the customer concern was a flashing MIL, operate the vehicle within the conditions for running DTC P0420 00. Refer to DTC P0420 .
2. Clear the DTCs with a scan tool.
3. Turn OFF the ignition for 60 s.
4. Start the engine.
5. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records.
6. If the DTC fails this ignition, a misfire still exists.