P03FBIgnition K Control Signal Circuit Low
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Can trigger limp mode
- How the car detects it
- Ignition K is one of up to twelve control signal lines (A to L) from the engine module to an ignition coil with integrated output stage or to an ignition module – plausibly the 11th channel, but the code standard leaves the assignment to the manufacturer. The code concerns this logic-level signal, not the coil's primary circuit (coil K has its own codes, P0361 and P2330 ff). P03FB means the signal stays too low – typically the control line is shorted to ground or the input of the output stage is shorted, so the driver never sees a high level. The coil fires wrongly or not at all; the misfire usually also sets P0300 ff, and many modules shut off injection to that cylinder to protect the catalyst. No manufacturer document available to us uses this code – it would only concern twelve-cylinder engines, whose makers publish no OBD summaries; GM and Ford tables stop at eight and ten cylinders.
- What you may notice
- Check engine light on, may flash with severe misfire
- Misfire on the cylinder of this channel, rough running
- Loss of power, cylinder possibly shut off
- Likely causes
- LikelyControl line shorted to ground (chafed harness)
- PossibleInput of the coil output stage shorted
- PossibleMoisture or corrosion in the connector
- RareDriver in the engine module
- Inspection (ITP)
- Matters for the ITP. While the check-engine light is on, the car fails the emissions check.
- Repair
- Medium · Usually a job for a workshop.Typical cost: €80 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.