OBD-II Code · Ignition
P0351
Ignition Coil A Primary/Secondary Circuit
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Not for long
Driving on this one risks further damage. Get it to a shop rather than carrying on with it.
Indicative cost (USD)
$80–$300
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
Coil pack 1 fault.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
- Misfire
- Rough running
Likely causes
- Failed coil 1Most common
- Wiring
- PCM driver
Read the full diagnostic procedureP0351 means the ECM saw a primary or secondary circuit fault specifically on the cylinder 1 ignition coil driver — either the trigger pulse never ret…
P0351 means the ECM saw a primary or secondary circuit fault specifically on the cylinder 1 ignition coil driver — either the trigger pulse never returned the expected back-EMF flyback signature (open primary, open secondary, or fouled spark path) or the driver transistor inside the ECM detected an over-current/under-current condition.
Cylinder 1 convention matters here
Ford Modular 4.6/5.4 V8 = front-right (passenger side), GM LS V8 = front-left (driver side), Chrysler Hemi = front-right, BMW inline-6 = front of engine (timing-chain end), Toyota 2GR-FE V6 = front bank passenger side cylinder 1. Cheapest-first diagnostic: swap the cylinder 1 coil with cylinder 3's coil, clear codes, and run a drive cycle — if the code moves to P0353, you've confirmed a $35-$120 coil failure. If P0351 stays at cylinder 1, backprobe the COP connector: B+ pin should read 12.0-12.6V key-on, and the trigger wire should show a clean ECM-commanded square-wave pulse on a scope (0V to 5V or 0V to 12V depending on platform, ~3-6ms dwell at idle). No trigger signal = broken trigger wire between ECM and coil (resistance check, repair the wire) or a failed ECM coil driver (rare but real). Don't replace the ECM until you've confirmed power, ground, trigger wire continuity, and a known-good coil — coil-driver-failure ECM diagnosis gets botched constantly because techs skip the wire-integrity step.
Vehicle-specific patterns2004-2010 Ford F-150/Expedition 5.4L 3V Triton is the volume P0351 platform — the cylinder 1 COP boot carbon-tracks to the head from heat soak on the…
- 2004-2010Ford F-150/Expedition 5.4L 3V Triton is the volume P0351 platform — the cylinder 1 COP boot carbon-tracks to the head from heat soak on the front-passenger cylinder, and Ford TSB 08-7-6 covers the updated coil/boot kit.
- 2005-2013Chevy/GMC 5.3L/6.0L LS truck V8s throw P0351 from cracked Delphi D585 coils — the epoxy potting cracks and lets moisture into the primary winding, and the OE fix is the updated D514A coil ($35-$60 each).
- 2007-2013BMW N52/N54 inline-6 throws P0351 from failed Bosch/Eldor coils — Eldor coils (red top) fail in batches, and BMW SI B12 04 08 covers the swap to updated Bosch units.
- 2007-2012Nissan Altima/Maxima/Murano 3.5L VQ35DE throws P0351 from cylinder 1 coil failure caused by valve cover gasket oil leak fouling the coil boot — replace both gasket and coil or it returns in weeks.
- 2003-2009Toyota 4Runner/FJ 4.0L 1GR-FE has Denso COP failures on cylinder 1 that often correlate with heat-soak after long highway runs.
Estimated repair$35 (one coil) to $480 (full coil set + valve cover gasket on a VQ35).
Look up another code
P0351 — frequently asked
What does a P0351 code mean?
Coil pack 1 fault.
What causes a P0351 code?
Common causes: Failed coil 1; Wiring; PCM driver.
What are the symptoms of a P0351 code?
Typical symptoms: Check engine light; Misfire; Rough running.
Is it safe to drive with a P0351 code?
Not for long. Driving on this one risks further damage. Get it to a shop rather than carrying on with it. Estimated repair: $80-$300.
How do I diagnose a P0351 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
More free tools