Parts
$20–80
P0351 — Ignition Coil A Primary/Secondary Circuit
CAUTIONIs it safe to drive? Cylinder A is likely misfiring — drivable to a shop but a flashing CEL means stop driving to avoid destroying the catalytic converter.
What P0351 means
The ECM monitors the voltage signal coming back from each ignition coil to confirm it fired. 'Circuit' means it saw an unexpected voltage — either the coil didn't fire at all, fired weakly, or the wiring to it has a fault.
Most likely causes (in order)
- Coil-on-plug unit for Coil A failed (most common)
- Connector pins corroded or backed out
- Wiring harness damaged between ECM and coil
- Spark plug fouled and overloading the coil
- ECM driver circuit for coil A (rare, but a dead ECM driver kills coils too)
Symptoms you might notice
- rough idle
- single-cylinder misfire
- CEL flashing under acceleration
- hesitation
What to check first
Swap Coil A with an adjacent coil (same engine family, same connector) and see if the corresponding misfire code follows it to the new position — this confirms the coil is the fault, not the wiring.
Repair cost & difficulty
Labor
0.5–1 hr
Difficulty
Easy DIY