What P0351 means
Modern engines have one coil-on-plug ignition coil per cylinder, with the output stage either in the engine module or in the coil itself.
How the engine computer detects it
P0351 monitors the primary control circuit of coil A – the line from the engine module to the coil or its built-in output stage – for an open circuit or high resistance. GM's module measures the voltage with its low-side driver off and flags an open circuit above 30 kΩ in 50 of 63 samples (2018 engines in the first trip, older ones after two); Ford checks continuously within 1 s, expecting a primary-current feedback for every ignition command, and shuts off injection to that cylinder for 30 s at a time. Short circuits and the secondary side have their own codes (P2300 ff). Coil A usually serves cylinder 1, but the assignment is up to the manufacturer.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Misfire and rough running on cylinder 1, often also P0301
- Loss of power, jerking under load
- Cylinder shut off (injection off), risk to the catalyst if driven on
Common causes
- Ignition coil A faulty (output stage in the coil or primary winding open) Most likely
- Connector at the coil corroded, loose or with a spread pin Most likely
- Control, supply or ground wire open or chafed Possible
- Fuse or relay of the coil supply (then usually several codes) Less likely
- Driver in the engine module faulty Less likely
How to diagnose P0351
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: ignition coil a, ignition wiring, engine control module.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Vehicles that report P0351 most
| Vehicle | Years | Reports | Share | Median miles |
|---|---|---|---|---|
| Ford Escape | 2005–2006 | 7 | 95k |
Counts of owner complaints to the NHTSA that mention P0351 (15 in total), not failure rates: popular models get more complaints simply because more of them are on the road. Models with fewer than 3 complaints are left out.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 3
- Ignition system or misfire
- 51
- Specific fault
Questions drivers ask
Can I drive with code P0351?
Drive gently and only as far as you need to. The engine computer may limit power to protect the engine, so avoid highways and heavy traffic until it's fixed. If the check engine light starts flashing, pull over.
Will my car pass an emissions inspection with P0351?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Can I fix P0351 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: easy. Start with the cheapest checks before replacing expensive parts.
Often reported together
Codes that owners mention in the same NHTSA complaints as P0351. They can point to a shared cause, so it's worth checking them together.
- P0354Ignition Coil D Primary Control Circuit/Open8 complaints
- P0352Ignition Coil B Primary Control Circuit/Open5 complaints
- P0353Ignition Coil C Primary Control Circuit/Open5 complaints
- P0355Ignition Coil E Primary Control Circuit/Open4 complaints
- P0356Ignition Coil F Primary Control Circuit/Open4 complaints
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.