DTC P0303: Cylinder 3 Misfire Detected: Troubleshooting

TROUBLESHOOTING CHART

Step	Action	Value(s)	Yes	No
1	Perform an On-Board Diagnostic (OBD) System Check. Is the system check complete?	-	Go to Step 2	Go to On-Board Diagnostic (OBD II) System Check
2	Install a scan tool to the Data Link Connector (DLC). Turn the ignition ON, with the engine OFF. Request Diagnostic Trouble Codes (DTCs). Is the DTC P0300 set?	-	Go to applicable DTC table	Go to Step 3
3	Perform a visual/physical inspection. Make any repairs that are necessary. Is the repair complete?	-	Go to Step 25	Go to Step 4
4	Start the engine and allow it to idle. Are any current misfire counters incrementing?	-	Go to Step 5	Go to Step 6
5	Are all counters equal (within a percentage of each other)?	-	Go to Step 7	Go to Step 11
6	Turn the ignition ON, with the engine OFF. Review the Freeze Frame Data, and note the parameters. Operate the vehicle within the Freeze Frame conditions and conditions for setting this DTC as noted. Are any current misfire counters incrementing?	-	Go to Step 5	Go to Diagnostic Aids
7	Turn the engine OFF. Install a fuel pressure gauge to the fuel rail. Observe the fuel pressure with the engine running. Is the fuel pressure within the specified value?	284 - 325 kPa (41 - 47 psi)	Go to Step 8	Go to "Fuel System Diagnosis"
8	Check the fuel for contamination. Is the fuel OK?	-	Go to Step 9	Go to Step 10
9	Check for a basic engine problem and repair as necessary. Is the repair complete?	-	Go to Step 25	-
10	Replace the contaminated fuel. Is the repair complete?	-	Go to Step 25	-
11	Turn the engine OFF. Disconnect the fuel injector harness connector. Install a spark tester on cylinder #3. Check the engine for a spark. Is a spark observed?	-	Go to Step 12	Go to Step 21
12	Replace any malfunctioning spark plugs. Is the repair complete?	-	Go to Step 25	Go to Step 13
13	Turn the engine OFF. Disconnect the cylinder #3 fuel injector connector from the injector. Install an injector test light on the injector harness connector terminal 1. Crank the engine and note the test light. Does the injector test light blink?	-	Go to Step 14	Go to Step 15
14	Perform the FUEL INJECTOR BALANCE TEST . Are the fuel injectors OK?	-	Go to Step 9	Go to Step 16
15	Disconnect the injector test light. With a test light connected to ground, probe the ignition feed terminal 2 of the injector harness connector. Crank the engine. Does the test light illuminate?	-	Go to Step 17	Go to Step 19
16	Replace any malfunctioning fuel injectors. Is the repair complete?	-	Go to Step 25	-
17	Check the affected fuel injector driver circuit for an open or short to voltage. Is a problem found?	-	Go to Step 18	Go to Step 23
18	Repair the open or the shorted fuel injector driver circuit. Is the repair complete?	-	Go to Step 25	-
19	Repair the open ignition feed circuit between the fuel injector harness connector and the fuel injector connector. Is the repair complete?	-	Go to Step 25	-
20	Inspect the Engine Control Module (ECM) connector and connections. Are the connections OK?	-	Go to Step 21	Go to Step 22
21	Check the affected cylinder ignition control circuit for an open or short and repair as needed. Is the repair complete?	-	Go to Step 25	Go to Step 24
22	Repair the connector or connections. Is the repair complete?	-	Go to Step 25	-
23	Turn the ignition OFF. Replace the ECM. Is the repair complete?	-	Go to Step 25	-
24	Replace the faulty ignition coil. Is the repair complete?	-	Go to Step 25	Go to Step 23
25	Using a scan tool, clear the DTCs. Start the engine and idle at normal operating temperature. Operate the vehicle within the conditions for setting the DTC as noted. Does the scan tool indicate that this diagnostic run and pass?	-	Go to Step 26	Go to Step 2
26	Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed?	-	Go to applicable DTC table	System OK