Faulty ignition coil A (internal open circuit or failed driver); Damaged, chafed or corroded wiring in the coil control circuit; Loose, corroded or damaged coil connector terminals; Missing or poor power supply or earth to the coil; Worn spark plug or excessive plug gap putting strain on the coil; Fault in the engine control unit driver circuit.

P0351

Ignition Coil A Primary Control Circuit/Open.

Generic
Powertrain
Generic code
Medium severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
3: AreaIgnition system or misfire
51: FaultThe specific fault in that area

What it means

P0351 means the engine control unit has detected a fault in the primary control circuit of ignition coil A, which is usually the coil for cylinder 1. The control unit monitors the coil driver signal and found it open circuit or out of the expected range. Which cylinder 'A' refers to, and whether the coil has its own driver electronics, depends on the engine.

Symptoms

Engine misfire, rough running or hesitation
Malfunction indicator lamp on, possibly flashing under load
Hard starting or no start
Loss of power and poor fuel economy
Fuel smell from the exhaust or engine running in limp mode

Possible causes

Faulty ignition coil A (internal open circuit or failed driver)likely
Damaged, chafed or corroded wiring in the coil control circuitlikely
Loose, corroded or damaged coil connector terminalslikely
Missing or poor power supply or earth to the coilpossible
Worn spark plug or excessive plug gap putting strain on the coilpossible
Fault in the engine control unit driver circuitrare

How to diagnose

Read the stored codes and freeze frame data to see load, rpm and temperature when the fault set, and check for related misfire codes
Confirm which cylinder coil A is for on this engine using the manufacturer's data
Visually inspect the coil connector and wiring for damage, heat, oil contamination, corrosion or bent pins
Check for misfire counts on cylinder 1 using live data
Swap coil A with another cylinder's coil and see whether the fault or misfire follows the coil
Check the coil's power supply, earth and control signal with a multimeter or oscilloscope against specification
Test the control wire for continuity and for short circuits to earth or supply back to the control unit
Inspect the spark plug for wear, fouling or incorrect gap

How to fix

Replace the faulty ignition coil
Repair or replace damaged wiring or the connector terminals
Restore the power supply or earth connection to the coil
Replace worn spark plugs with the correct type and set the gap to specification
Replace or repair the control unit only after all wiring and component faults have been ruled out
Clear the code and road test to confirm the fault does not return

Can I keep driving?

Medium severity

Short, gentle driving is possible, but a misfire can overheat and damage the catalytic converter, so get it fixed soon. If the warning lamp is flashing, avoid heavy load and stop driving as soon as it is safe.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.