OBD-II code · Powertrain (generic)
P0540 Intake Air Heater A Circuit
Intake Air Heater A Circuit: an electrical fault is present in the circuit. Used on diesel and some petrol engines for cold-start emissions and starting reliability.
Is it safe to drive with P0540?
Usually safe to drive in the short term. Get it diagnosed when convenient, sooner if the car drives differently.
Common causes
- Most likelyHeater element open or shorted
- PossibleHeater relay defective
- Less likelyWiring fault
Repair at a glance
- Difficulty
- Medium
- DIY friendly
- Best left to a mechanic
- Typical labour
- 0.5–2 h
- Emissions test
- Likely to fail
- Parts involved
- Intake Air Heater, Heater Relay, Heater Wiring
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.