P0543Intake Air Heater A Circuit Open
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- Needs a drive cycle to confirm a fix
- How the car detects it
- Some diesels – typically Cummins engines in Ram pick-ups and commercial vehicles, and Iveco – heat the intake air with a grid heater in the intake manifold instead of or alongside glow plugs. It draws very high current through a relay (on recent Ram a solid-state relay) and is switched by the engine module before and after starting; CARB requires cold-start aids to be monitored. P0543 means an open circuit at heater A – in the control line or relay coil, or depending on the maker in the power circuit or heating element itself. It is detected by driver diagnosis with the output off, by a missing voltage dip on switching on or by a missing temperature rise. No manufacturer document available to us uses this code; GM's Duramax LML has an intake heater but reports it under its own codes P154A–P154D.
- What you may notice
- Check engine light on
- Starting problems in the cold
- White smoke or knocking while warming up
- Likely causes
- LikelyHeating grid burnt out
- PossibleRelay coil or contact open
- PossibleBroken cable, loose nut or ring terminal at the grid
- RareFusible link in the heater circuit
- 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: €40 – €450
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.