P2606Intake Air Heater B Circuit Range/Performance
- 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
- P2606 means heater B in the intake does respond, but the current it draws or the voltage drop across its circuit lies outside the window the engine controller expects. Mack documents P2604-7F and P2606-7F for 2014-2017 trucks with MP7, MP8 and MP10 engines and puts them down to extra circuit resistance from corrosion inside the master disconnect switch, so inspecting those contacts comes first. Volvo's 2020 software change log for heavy-truck engines lists P2606-7F next to the heater A code as a result of the preheater relay issue addressed by new EMS software. Unlike P2605, P2607 and P2608, the circuit is not open or shorted but merely implausible; P2604 is the same check for heater A. Cold starts may become sluggish and the engine may smoke white until warm.
- What you may notice
- Sluggish cold starts
- White smoke until the engine is warm
- MIL on
- Likely causes
- LikelyExtra resistance from corroded contacts, e.g. in the master disconnect switch
- PossibleWorn preheat relay contacts
- PossibleAged heater element with changed resistance
- RareOutdated engine software (update published by the maker)
- 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: €50 – €700
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.