P0352
Ignition Coil "B" Primary/Secondary Circuit
What it means
The ECU has detected a fault in the circuit for ignition coil B. On most engines coil B fires cylinder 2, though some engines number them differently, so check a service manual. A coil that does not fire causes a misfire in its cylinder.
Is it safe to drive?
Avoid driving if the check engine light is flashing. A flashing light means a severe misfire that is dumping unburned fuel into the exhaust, which can overheat and destroy the catalytic converter within minutes. If the light is steady, drive gently to a repair shop.
Symptoms
- Check engine light on
- Misfire, often with a cylinder 2 misfire code
- Rough running and loss of power
- Hard starting
Probable causes
Most likely first
- 1Failed ignition coil
- 2Damaged connector or wiring to the coil
- 3Missing power to the coil (blown fuse or relay)
- 4Oil or water in the spark plug well
- 5ECU coil driver fault (rare)
How to diagnose it
Work through these in order before buying parts
- 1Record the code and its freeze frame data (speed, load, temperature when it set), then clear it and see if it comes back.
- 2Inspect the coil connector and look for oil or water in the spark plug tube.
- 3Swap the coil with another cylinder and see if the fault follows it.
- 4With the key on, check for battery voltage at the coil power wire and a good ground.
- 5Check the ECU trigger signal with a test light or oscilloscope while cranking.
- 6Check for technical service bulletins (TSBs) or software updates for your make and model; some codes have known factory fixes.
Common fixes
- Replace the ignition coil
- Repair the wiring or connector
- Fix oil leaks into the plug well (valve cover gasket or tube seals)
This information is general guidance for all makes. Exact causes, specifications and procedures vary by vehicle, so confirm with your service manual or a qualified mechanic before replacing parts.