Case Study: Explorer misfire, MIL on after owner replaced coil

March 22, 2023

After the owner tried replacing the #5 coil, to repair a P0305 misfire DTC, this Explorer ended up at the shop with a hard misfire and the MIL illuminated in the instrument cluster.

Richard Diegle

Related To:

ALLDATA

Vehicle: 2003 Ford Explorer, 2WD, V8-4.6L, VIN W, Automatic transmission/transaxle

Mileage: 196,459

Problem: After the owner tried replacing the #5 coil, to repair a P0305 misfire diagnostic trouble code (DTC), this Explorer ended up at the shop with a hard misfire and the malfunction indicator light (MIL) illuminated in the instrument cluster.

Case Details: The technician connected a scan tool and retrieved the following codes:

P0305 – Cylinder #5 Misfire Detected
P0340 – Camshaft Position Sensor A Circuit (Bank 1 Or Single Sensor).

While discussing diagnostic strategy with the technician, an ALLDATA Tech-Assist consultant noted that the two DTCs displaying together strongly suggested that harness connectors for coil #5 and the camshaft position sensor (CMP) may be swapped.

Note: On this vehicle, the #5 Coil-Over-Plug (COP) connector (C115) and the CMP sensor connector (C180) are not only adjacent to one another on the driver's side cylinder head, but they are nearly identical. The consultant recommended to first verify that each connector was plugged into the correct component.

After a quick inspection, the technician found the connectors C115 and C180 were indeed swapped.

Confirmed Repair: The technician installed the connectors onto the correct components, cleared the DTCs and went for a test drive. Neither the DTCs nor the misfire returned. Fixed!

Reprinted with permission from ALLDATA.

About the Author

Richard Diegle | Senior Automotive Editor for ALLDATA

Rich Diegle has been in the automotive industry since 1978. After graduating from a local community college, he began working at a Nissan dealership as a used car technician. Since then, he’s worked as a Nissan and ASE master automotive technician, shop owner, marketing copywriter, automotive editor, public relations manager, instructor, ALLDATA Tech-Assist team manager, and a senior automotive editor.