Cause
Incorrect spark plug gap or heat range
Plugs fitted at the wrong gap, or of the wrong heat range for the engine. Too wide a gap needs voltage the coil may not have; too cold a plug fouls and too hot a plug invites pre-ignition — and because the plugs are new, they are the last thing anybody suspects. Worth checking whenever a misfire dates from a service.
Typically an easy fix. Often worth checking before paying anyone to look.
Some of these codes mean you should stop driving
7 of the 9 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 (9)
Codes where this is a likely explanation first, rather than merely a possible one.
- P034C Ion Sense System Performance Likely for this code Moderate
- P2302 Ignition Coil A Secondary Circuit Likely for this code Stop driving High
- P2305 Ignition Coil B Secondary Circuit Stop driving High
- P2314 Ignition Coil E Secondary Circuit Stop driving High
- P2317 Ignition Coil F Secondary Circuit Stop driving High
- P2323 Ignition Coil H Secondary Circuit Stop driving High
- P2329 Ignition Coil J Secondary Circuit Stop driving High
- P2335 Ignition Coil L Secondary Circuit Stop driving High
- P2336 Cylinder 1 Above Knock/Combustion Vibration Sensor Threshold 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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Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
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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