How do I know which coil is bad?
Documented on the 2012 Ford Mustang GT build
Published February 26, 2026
Read the OBD-II codes (P030x) to identify the misfiring cylinder.
Full Answer
Read the OBD-II codes (P030x) to identify the misfiring cylinder. You can also swap the suspect coil with a known-good cylinder — if the misfire moves to the other cylinder, the coil is the culprit.
Documented In This Build
Related Knowledge
What torque should I use for the coil mounting bolt?Do I need to replace the spark plug when replacing a coil?Can I clear the code and drive without replacing the coil?How do I know if the PCV grommet is bad?What causes oil to fill the spark plug wells?Can I drive the car if the plugs are covered in oil?How often should I clean the fuel injectors?Can I use a pour-in fuel additive instead of an inline cleaning kit?
Related Parts
Ignition coil pack (single cylinder, coil-on-plug)
$100
Replacement spark plug (recommended)
$12
Dielectric grease
$5
Related Tools
Torque wrench
OBD-II scanner / code reader
Ratchet
10mm socket
Extension bar
Spark plug socket (5/8" or 13/16")
