Test Description

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

1: The Diagnostic System Check - Vehicle prompts the technician to complete some basic checks and store the Freeze Frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
2: This step verifies whether the misfire is present. The scan tool will display increasing counts in one or more of the Misfire Current Cyl. # parameter of the misfiring cylinder when a misfire is occurring.
4: If the Misfire Current Counters are incrementing, but the engine is NOT misfiring, this indicates a mechanical condition. For example, an accessory drive belt could cause this condition.

DTC P0300

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views or Splice Pack Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	IMPORTANT: The engine may only misfire when the engine is under a load. An engine load may be necessary to verify the condition. Turn ON the ignition, with the engine OFF. Clear the DTCs with a scan tool. Start the engine and allow the engine to idle. Allow the engine to reach operating temperature. Monitor the Misfire Current Cyl. 1-6 Counter parameters with a scan tool. Are any of the Misfire Current Counters incrementing?	-	Go to Step 4	Go to Step 3
3	Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. 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. Did the DTC fail this ignition?	-	Go to Step 4	Go to Diagnostic Aids In This Test
4	Is the engine misfiring?	-	Go to Step 5	Go to Symptoms - Engine Mechanical
5	Observe the DTC Info with a scan tool. Is DTC P0201, P0202, P0203, P0204, P0205, P0206, P0335, P0336, P0401, P0403, P0404, P0406, P2647, P2648, or P2649 also set?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	Go to Step 6
6	Is there an engine mechanical noise?	-	Go to Symptoms - Engine Mechanical	Go to Step 7
7	Is there more than one misfire DTC set?	-	Go to Step 8	Go to DTC P0301-P0306
8	Inspect or test for the following conditions: Inspect the vacuum hoses for splits, kinks, and proper connections. Inspect the throttle body and the intake manifold for vacuum leaks. Inspect the crankcase ventilation valve and/or system for any vacuum leaks. Refer to Crankcase Ventilation System Inspection/Diagnosis . Test for the correct fuel pressure. Refer to Fuel System Diagnosis . Inspect the fuel system for any restrictions, leaks or fuel contamination. Refer to Fuel System Diagnosis or Alcohol/Contaminants-in-Fuel Diagnosis . Inspect for fouled or damaged spark plugs. Determine what caused the spark plugs to foul. Refer to Spark Plug Inspection and Spark Plug Replacement . Inspect the exhaust system for restrictions. Refer to Restricted Exhaust . Inspect the splice pack for the ignition 1 circuits of the ignition coils for water intrusion and poor connections. Refer to Testing for Intermittent Conditions and Poor Connections . Inspect the engine control grounds for being clean, tight, and in the correct location. Repair as necessary. Did you find and correct the condition?	-	Go to Step 9	Go to Symptoms - Engine Mechanical
9	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. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 10
10	In order to ensure that the performance of the catalyst has not been affected by the fault that set this DTC, operate the vehicle within the conditions for running and setting DTC P0420/0430 and verify that DTC P0420/0430 runs and passes. Refer to DTC P0420 or P0430 . Does the DTC run and pass?	-	Go to Step 11	Go to DTC P0420 or P0430
11	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	System OK