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2005 Mercury Sable P0301 and P0316 Fault: Misfire and Check Engine Light After Spark Plug and Coil Replacement

Model: 2005 mercury sable Fault Code: P0301 Posted: 2015-10-09 17:50

I own a 2005 Mercury Sable, and the check engine light came on after I replaced both spark plugs and coil packs. The vehicle now exhibits hesitation, jerking, and bucking during acceleration. Diagnostic trouble codes P0301 (cylinder 1 misfire) and P0316 (initial start failure) are present. What could be causing this issue? Any guidance or troubleshooting steps would be greatly appreciated.

Related fault codes

P0301P0316

Comments (2)

Anonymous 2015-10-10 11:05

You replaced the coil pack — is there spark at cylinder #1? A misfire could also stem from a faulty injector. What did the old spark plug look like? Was it wet, dry, black, or tan? Here are some diagnostic steps to help identify the root cause: 1) Use a fuel pressure gauge to check fuel pressure and observe any drop during a KOEO (Key On, Engine Off) test. 2) Connect a noid light to cylinder #1's injector to verify proper signal. 3) Perform a compression test to rule out mechanical issues. Note: The issue may not be related to individual coil packs alone.

Anonymous 2015-10-10 13:56

Was the check engine light already on before you replaced the spark plugs and coil assemblies? Since you've already replaced both, ignition-related causes are less likely. A dirty, restricted, or stuck injector could be the culprit. A drop test on the injector would confirm this. Additionally, checking Mode 6 of the Ford misfire counter (available via OBD2 scan tools) can determine if current misfires are occurring. This requires specialized diagnostic equipment to perform accurately.