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P0307 — Cylinder 7 Misfire Detected

Generic OBD-II · all makesPowertrain (engine & transmission)

The powertrain control module has detected a misfire in cylinder 7. This means the engine is not completing a full combustion cycle in that cylinder.

Symptoms

What causes it — most likely first

1. Faulty spark plug in cylinder 7

The spark plug may be fouled, worn, or not firing at the proper voltage, causing incomplete combustion.

2. Faulty ignition coil for cylinder 7

A failing coil can deliver insufficient spark, leading to a misfire.

3. Malfunctioning fuel injector for cylinder 7

A clogged or leaking injector can starve the cylinder of fuel, resulting in a misfire.

4. Low compression due to valve or piston ring issues

Worn or burnt valves, damaged piston rings, or a leaking head gasket can reduce cylinder pressure and cause a misfire.

5. Mechanical timing or camshaft wear affecting cylinder 7

If the camshaft timing is off or the lifter is faulty, cylinder 7 may not receive proper valve operation.

6. Wiring or connector problem to cylinder 7 coil or injector

Corroded terminals, broken wires, or a poor ground can interrupt the signal to the coil or injector; a PCM failure is uncommon and would be considered only after other components are verified.

How it's diagnosed

  1. Inspect the spark plug, coil, injector, and wiring for cylinder 7 for damage or wear.
  2. Swap the cylinder 7 coil with a known good coil from another cylinder to see if the misfire follows the coil.
  3. Swap the cylinder 7 injector with a known good injector to determine if the issue is injector-related.
  4. Perform a compression test on cylinder 7 and compare it to the other cylinders to identify mechanical problems.
  5. Scan for additional fault codes and, if all other tests are clear, evaluate the PCM only as a last resort.

Code facts & related codes

SystemPowertrain (engine & transmission)
StandardizationSAE generic — identical on every make
Related codesP0300 — Randommultiple Cylinder Misfire DetectP0301 — Cylinder 1 Misfire DetectedP0302 — Cylinder 2 Misfire DetectedP0303 — Cylinder 3 Misfire DetectedP0304 — Cylinder 4 Misfire DetectedP0305 — Cylinder 5 Misfire Detected

Frequently asked

Will replacing the PCM fix P0307?

No, the PCM is rarely the cause; most P0307 codes are resolved by repairing or replacing a component in cylinder 7 such as the spark plug, coil, or injector.

Can a dirty air filter cause a cylinder 7 misfire?

A dirty air filter affects overall engine performance but does not typically cause a misfire in a specific cylinder.

Is it safe to continue driving with a P0307 code?

Driving with a misfire can damage the catalytic converter and reduce engine efficiency, so it should be diagnosed and repaired promptly.