Cause
Worn or fouled spark plugs
Electrodes worn to a wider gap, or deposits shorting the spark to earth. Gaps widen slowly with mileage and eventually exceed what the coil can bridge under load — so the misfire shows under acceleration first while the idle still seems clean.
Typically an easy fix. Often worth checking before paying anyone to look.
Some of these codes mean you should stop driving
40 of the 50 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (50)
Codes where this is a likely explanation first, rather than merely a possible one.
- P0300 Random/Multiple Cylinder Misfire Detected Likely for this code Stop driving High
- P0301 Cylinder 1 Misfire Detected Likely for this code Stop driving High
- P0302 Cylinder 2 Misfire Detected Likely for this code Stop driving High
- P0303 Cylinder 3 Misfire Detected Likely for this code Stop driving High
- P0304 Cylinder 4 Misfire Detected Likely for this code Stop driving High
- P0305 Cylinder 5 Misfire Detected Likely for this code Stop driving High
- P0306 Cylinder 6 Misfire Detected Likely for this code Stop driving High
- P0307 Cylinder 7 Misfire Detected Likely for this code Stop driving High
- P0308 Cylinder 8 Misfire Detected Likely for this code Stop driving High
- P0309 Cylinder 9 Misfire Detected Likely for this code Stop driving High
- P0310 Cylinder 10 Misfire Detected Likely for this code Stop driving High
- P0311 Cylinder 11 Misfire Detected Likely for this code Stop driving High
- P0312 Cylinder 12 Misfire Detected Likely for this code Stop driving High
- P0314 Single Cylinder Misfire — Cylinder Not Specified Likely for this code Stop driving High
- P0316 Engine Misfire Detected on Startup (First 1000 Revolutions) Likely for this code Moderate
- P034C Ion Sense System Performance Likely for this code Moderate
- P0350 Ignition Coil Primary/Secondary Circuit/Open Likely for this code Stop driving High
- P0351 Ignition Coil A Primary Control Circuit/Open Likely for this code Stop driving High
- P0352 Ignition Coil B Primary Control Circuit/Open Likely for this code Stop driving High
- P0353 Ignition Coil C Primary Control Circuit/Open Likely for this code Stop driving High
- P0354 Ignition Coil D Primary Control Circuit/Open Likely for this code Stop driving High
- P0355 Ignition Coil E Primary Control Circuit/Open Likely for this code Stop driving High
- P0356 Ignition Coil F Primary Control Circuit/Open Likely for this code Stop driving High
- P0357 Ignition Coil G Primary Control Circuit/Open Likely for this code Stop driving High
- P0358 Ignition Coil H Primary Control Circuit/Open Likely for this code Stop driving High
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
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What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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