Test Description

The number below refers to the step number on the diagnostic table.

2: If the actual CKP variation values are not within the learned values, the misfire counters may increment.

DTC P0300 - P0308

Step	Action	Values	Yes	No
1	Did you perform the Diagnostic System Check - Vehicle?	-	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	IMPORTANT: You must perform the Crankshaft Position (CKP) System Variation Learn Procedure before proceeding with this diagnostic table. Refer to CKP System Variation Learn Procedure . If vehicle is equipped with a manual transmission, then turn ON the A/C system, headlights, blower motor, and heated back glass when testing for engine misfires at idle conditions. Start the engine. Allow the engine to idle or operate within the conditions listed in the Freeze Frame/Failure Records. Monitor all of the Misfire counters with the scan tool. Are any of the Misfire current counters incrementing?	-	Go to Step 3	Go to Diagnostic Aids
3	Are any DTCs other than DTC P0300-P0308 set?	-	Go to Diagnostic Trouble Code (DTC) List - Vehicle	Go to Step 4
4	Can any abnormal engine noise be heard?	-	Go to Symptoms - Engine Mechanical	Go to Step 5
5	Does the scan tool indicate that the heated oxygen sensor (HO2S) bank 1 sensor 1 or HO2S bank 2 sensor 1 voltage parameters are below the specified value?	200 mV	Go to DTC P0131 or P0151	Go to Step 6
6	Does the scan tool indicate that the HO2S bank 1 sensor 1 or HO2S bank 2 sensor 1 voltage parameters are fixed above the specified value?	900 mV	Go to DTC P0132 or P0152	Go to Step 7
7	Inspect the following components: The vacuum hoses and seals for splits, restrictions, and improper connections-Refer to Emission Hose Routing Diagram . The throttle body and intake manifold for vacuum leaks The crankcase ventilation system for vacuum leaks-Refer to Crankcase Ventilation System Inspection/Diagnosis . The engine control module (ECM) grounds for corrosion and loose connections-Refer to Ground Distribution Schematics . The exhaust system for restrictions-Refer to Restricted Exhaust in Engine Exhaust. The fuel for contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) . Did you find and correct the condition?	-	Go to Step 19	Go to Step 8
8	IMPORTANT: An erratic or inconsistent spark is considered a no spark. Turn OFF the ignition. Disconnect the spark plug wire from the spark plug that corresponds to the affected cylinder. Refer to Spark Plug Wire Replacement . Install the J 26792 Spark Tester. See Special Tools . Start the engine. Does the spark jump the tester gap?	-	Go to Step 10	Go to Step 9
9	Remove the spark plug wire for the affected cylinders. Refer to Spark Plug Wire Replacement . Inspect the spark plug wire. Refer to Spark Plug Wire Inspection . Measure the resistance of the spark plug wire with a DMM. Is the resistance within the specified value?	188-312 ohm	Go to Electronic Ignition (EI) System Diagnosis	Go to Step 18
10	Remove the spark plug from the cylinder that indicated a misfire. Refer to Spark Plug Replacement . Inspect the spark plug. Refer to Spark Plug Inspection . Does the spark plug appear to be OK?	-	Go to Step 11	Go to Step 12
11	Exchange the suspected spark plug with another cylinder that is operating properly. Refer to Spark Plug Replacement . Operate the vehicle under the same conditions that the misfire occurred. Did the misfire move with the spark plug?	-	Go to Step 17	Go to Step 15
12	Is the spark plug oil or coolant fouled?	-	Go to Symptoms - Engine Mechanical	Go to Step 13
13	Is the spark plug gas fouled?	-	Go to Step 16	Go to Step 14
14	Did the spark plug show any signs of being cracked, worn, or improperly gapped?	-	Go to Step 17	Go to Step 15
15	Perform the fuel injector coil test. Refer to Fuel Injector Coil Test . Did you find and correct the condition?	-	Go to Step 19	Go to Symptoms - Engine Mechanical
16	Perform the fuel system diagnosis. Refer to Fuel System Diagnosis . Did you find and correct the condition?	-	Go to Step 19	Go to Symptoms - Engine Mechanical
17	Replace the faulty spark plug. Refer to Spark Plug Replacement . Did you complete the replacement?	-	Go to Step 19	-
18	Replace the faulty spark plug wires. Refer to Spark Plug Wire Replacement . Did you complete the replacement?	-	Go to Step 19	-
19	Was the customer concern the malfunction indicator lamp (MIL) flashing?	-	Go to Step 20	Go to Step 21
20	Operate the vehicle at the specified value for 4 minutes. Operate the vehicle within the Conditions for Running the DTC P0420 or P0430 as specified in the supporting text. Refer to DTC P0420 or P0430 . Does the DTC run and pass?	2,500 RPM	Go to Step 21	Go to DTC P0420 or P0430
21	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 22
22	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