P0356Ignition Coil F Primary Control Circuit/Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- P0356 monitors the primary control circuit of ignition coil F – the line from the engine module to the coil or to its built-in output stage – for an open circuit or high resistance. Coil F usually serves cylinder 6, so the code only occurs on engines with at least 6 cylinders. GM's 6.2-litre V8s (LT4, LT5) flag an open circuit above 30 kΩ with the driver off in 50 of 63 samples, after two trips. Ford checks continuously from 200 rpm within 1 s, expecting a primary-current feedback for every ignition command, and then shuts off injection to that cylinder for 30 s at a time to protect the catalyst. GM bulletin PIP5038B describes coils on the 3.6-litre V6 (LLT) overheating from a permanently switched-on control signal; PIP5147 advises checking coil connectors for water. Short circuits have their own codes (P2315 ff).
- What you may notice
- Check engine light on
- Misfire and rough running on cylinder 6, often also P0306
- Loss of power, jerking under load
- Cylinder shut off (injection off), risk to the catalyst if driven on
- Likely causes
- LikelyIgnition coil F faulty (output stage in the coil or primary winding open)
- LikelyConnector at the coil corroded, wet or with a loose pin
- PossibleControl, supply or ground wire open or chafed
- RareDriver in the engine module faulty or software (permanent dwell)
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Easy · Often possible to do yourself.Typical cost: €40 – €250
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.