P0351 Code: Ignition Coil A Primary/Secondary Circuit Malfunction
🟠 Moderate severity · drivable
Drivable short-term, but cylinder 1 will misfire and raw fuel can damage the catalytic converter. Stop if the light flashes.
What P0351 means
There's an electrical fault in the ignition coil circuit for cylinder 1 (coil A). The computer can't fire that coil properly, so cylinder 1 loses spark and misfires — which is why P0351 often appears together with a P0301 cylinder 1 misfire.
Symptoms
- Check engine light on (may flash)
- Misfire or rough idle on cylinder 1
- Loss of power
- Poor fuel economy
Common causes
- most common: Faulty ignition coil on cylinder 1 (coil A)
- common: Damaged wiring or a loose connector at the coil
- less common: Ignition driver failure inside the engine computer (PCM)
How to fix it
| Fix | DIY? | Typical cost |
|---|---|---|
| Swap the cylinder 1 coil with another cylinder to see if the misfire follows the coil | Yes | $0–20 |
| Replace the cylinder 1 ignition coil | Yes | $50–200 |
| Repair damaged coil wiring or connector | Mechanic | $50–150 |
Frequently asked questions
Which cylinder is ignition coil A?
Coil A fires cylinder 1, coil B fires cylinder 2, and so on (coil H = cylinder 8). P0351 is the cylinder 1 coil circuit.
How do I confirm a bad coil on P0351?
Swap the cylinder 1 coil with another cylinder and re-scan. If the misfire moves to the new cylinder, the coil is the culprit.
Does P0351 cause a misfire?
Yes — if the coil can't fire, cylinder 1 misfires, which is why P0351 and P0301 often show up together.
Related codes
P0301
P0301 Code: Cylinder 1 Misfire Detected
P0350P0350 Code: Ignition Coil Primary/Secondary Circuit Malfunction
P0352P0352 Code: Ignition Coil B Primary/Secondary Circuit Malfunction
Related guide: The 10 Most Common Check Engine Codes →
Updated 2026-08. This page is informational and not a substitute for professional diagnosis.