P2608Intake Air Heater B Circuit High
- Generic OBD-II code · Powertrain
- Turns on the check-engine light
- Matters for the ITP
- How the car detects it
- P2608 is logged when the circuit of intake air heater B reads too high, for instance a short to battery positive on the control line or a relay that stays energized when it should be off. Volvo is the one maker that names it in public bulletins: the August 2020 EMS change log for heavy-truck engines lists P2608-00 among the preheater codes reduced by a relay robustness update, and Volvo's 2022 instruction for the pre-heat relay on 11 L and 13 L engines includes P2608-7E in its scope before replacing relay and supply cable. Deutz uses P0542 with the same meaning for its preheating relay. A heater stuck on drains the batteries and can overheat cables; a dead heater makes cold starts hard. P2607 is the low-side code, P2605 the open circuit.
- What you may notice
- MIL on
- Batteries run down after short trips or standstill
- Hard cold starts or white smoke
- Likely causes
- LikelyPreheat relay contacts welded or sticking closed
- PossibleControl or feedback wire shorted to battery positive
- RareEngine software needing the maker's update
- 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: €60 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.