Diagnostic Aids

WARNING: This page is about a different variant/trim than selected.

A Misfire DTC could be caused by an excessive vibration from sources other than the engine. Check for the following possible sources:

A tire or wheel that is out of round or out of balance
Variable thickness brake rotor or drum
An unbalanced drive shaft
Certain rough road conditions
a damaged accessory drive belt

DTC P0300 - Engine Misfire Detected

Step	Action	Values	Yes	No
1	Did you perform the Diagnostic System Check-Engine Controls?	-	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	Start the engine. Allow the engine to idle or operate within the conditions listed in the Freeze Frame Records. Monitor all of the misfire current counters with the scan tool. There are a total of 6 counters, 1 counter per cylinder. Are any of the misfire current counters incrementing?	-	Go to Step 3	Go to Diagnostic Aids
3	Are any DTCs from P0201-P0206 also set?	-	Go to Diagnostic Trouble Code (DTC) List	Go to Step 4
4	Are any DTCs from P0301-P0306 also set?	-	Go to Diagnostic Trouble Code (DTC) List	Go to Step 5
5	Does the scan tool indicate that any HO2S voltage parameters are fixed below the specified value?	200 mV	Go to DTC P0131, P0137, P0151, or P0157	Go to Step 6
6	Does the scan tool indicate that any HO2S voltage parameters are fixed above the specified value?	900 mV	Go to DTC P0132 or P0152	Go to Step 7
7	Visually and physically inspect the following items: The vacuum hoses for splits, kinks, and proper connections The throttle body and the intake manifold for any vacuum leaks The crankcase ventilation valve and/or system for any vacuum leaks The ECM ground-Verify that they are clean and secure. Repair as necessary. Did you find and correct the condition?	-	Go to Step 10	Go to Step 8
8	Inspect the fuel system for any restrictions, leaks or fuel contamination. Refer to Fuel System Diagnosis or Alcohol/Contaminants-in-Fuel Diagnosis (w/o Special Tool)Alcohol/Contaminants-in-Fuel Diagnosis (w/ Special Tool) . Repair as necessary. Did you find and correct the condition?	-	Go to Step 10	Go to Step 9
9	Perform the ignition system check. Refer to Electronic Ignition (EI) System Diagnosis . Repair as necessary. Did you find and correct the condition?	-	Go to Step 10	Go to Symptoms - Engine Mechanical in Engine Mechanical
10	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC run and pass?	-	Go to Step 11	Go to Step 2
11	With a scan tool, observe the stored information, Capture Info. Does the scan tool display any DTCs that you have not diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List	System OK