P030DIgnition B Control Signal Circuit/Open
- 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 B is one of the control signal lines from the engine module to an ignition module, ignition output stage or group of coils; which cylinders it serves is defined by the manufacturer, not by the code standard. The code concerns the logic-level control signal, not the coil's primary current (that has its own codes, P0351 ff and P2300 ff). P030D means the control line is open – the module sees a voltage with its driver off that indicates high resistance. No manufacturer using these codes was found; GM reports coil control faults as P0351 ff (open above 30 kΩ, first trip), so the description follows CARB and that analogy. The affected coils fire wrongly or not at all, causing misfire; many modules then shut off injection to those cylinders to protect the catalyst.
- What you may notice
- Check engine light on
- Misfire, jerking, rough idle
- Loss of power, possibly cylinders shut off
- Additional misfire codes P0300 ff
- Likely causes
- LikelyControl line or connector pin open (corrosion, pushed-back pin)
- PossibleIgnition module or coil with integrated driver of this group faulty
- PossibleSupply or ground of the ignition module faulty
- RareDriver stage 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 · Often possible to do yourself.Typical cost: €50 – €500
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.