P0352
Ignition Coil B 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
- 52
- FaultThe specific fault in that area
What it means
P0352 means the engine control unit has detected a fault in the primary control circuit of ignition coil B, usually an open circuit. The control unit monitors the coil driver signal or its feedback and sets the code when the expected switching or current response is missing. Which cylinder coil B serves depends on the engine and manufacturer.
Symptoms
- Engine misfire, especially under load or at idle
- Rough running or shaking at idle
- Malfunction indicator lamp on, possibly flashing during a misfire
- Hesitation or loss of power
- Hard starting or no start in some cases
- Increased fuel consumption
Possible causes
- Faulty ignition coil B (open primary winding or internal driver fault)likely
- Damaged, corroded or loose coil connector or terminalslikely
- Open circuit, high resistance or chafed wiring between the coil and the control unitpossible
- Missing or poor power supply or earth to the coilpossible
- Blown fuse or faulty relay feeding the ignition coils (depends on model)possible
- Fault within the engine control unit driver circuitrare
How to diagnose
- Read all stored and pending codes and note freeze frame data (load, rpm, temperature) to see when the fault occurred.
- Check the manufacturer information to identify which cylinder and coil is 'coil B' on this engine, as this varies.
- Inspect the coil connector and wiring for damage, corrosion, water ingress, heat damage or looseness.
- Check the relevant fuse and relay for the ignition supply.
- Swap coil B with a coil from another cylinder, clear the codes and see whether the fault or the misfire follows the coil.
- With the connector unplugged, test the coil primary resistance against the specification for that engine.
- Test the coil supply voltage and earth, and check the control wire for continuity and shorts using the wiring diagram.
- If the wiring and coil are good, check the control unit driver signal with a suitable oscilloscope before considering the control unit.
How to fix
- Replace the faulty ignition coil B, and check the spark plug condition for that cylinder at the same time.
- Repair or replace damaged connector terminals and clean up any corrosion.
- Repair or replace the open or damaged section of wiring.
- Restore the correct power supply or earth by renewing the faulty fuse, relay or earth connection.
- Repair or replace the engine control unit only if testing proves the driver circuit has failed.
Can I keep driving?
Medium severity
Short, gentle driving is usually possible, but have it fixed soon. Continued misfiring can overheat and damage the catalytic converter, so avoid heavy loads, and stop driving if the warning lamp flashes.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.