P2608
Intake Air Heater B Circuit High
Intake air heater
Generic OBD-II
Low
What it means
P2608 means the engine computer sees high voltage (usually an open circuit) in the "B" intake-air-heater circuit. The intake air heater warms incoming air to help cold starts and cut cold-start emissions, mostly on diesels. Once the engine is warm it runs normally; you may just notice harder cold starts and the check-engine light.
Low
Can I keep driving? Safe to drive — you may notice harder cold starts or brief rough warm-up in cold weather, but the engine runs normally once warm.
Common symptoms
What you'll notice
- Check-engine light on
- Harder starting in cold weather
- Brief rough running or white smoke just after a cold start (mainly diesels)
- No noticeable change in warm conditions
Common causes
Most likely first
- Faulty intake air heater element or relayLikely
- Open or high-resistance wiring in the heater 'B' circuitCommon
- Corroded or loose heater connectorCommon
- Blown fuse feeding the intake air heaterLess often
- Faulty PCM heater driver (rare)Less often
How to diagnose & fix
Work through it in order
- Read freeze-frame; confirm the B-circuit heater code and note any companion heater codes.
- Inspect the heater relay, fuse, and connector for corrosion or looseness.
- Measure the heater element resistance and supply voltage against spec.
- Check wiring between the PCM/relay and heater for opens or high resistance.
- Replace the heater element or relay if out of spec; clear and retest after a cold soak.
FAQ
Quick answers
Is it safe to drive with P2608?+
Yes. The intake air heater only assists cold starts, so the engine runs normally once warm. In cold climates you may just notice slightly harder starting until it's repaired.
Can I just clear P2608?+
You can, but the logic mainly runs at cold start, so it will return on the next cold start unless the heater circuit is repaired.
Related codes
Read & clear P2608 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX