P2605
Intake Air Heater B Circuit/Open
Intake air heater
Generic OBD-II
Low
What it means
P2605 means the PCM detected an open (broken) electrical circuit in the intake air heater's 'B' control side. The intake air heater warms incoming air to help the engine start and run cleanly in cold weather, especially on diesels. With the circuit open the heater cannot work, so cold starts are harder and smokier — but normal warm running and driving are unaffected.
Low
Can I keep driving? Safe to drive in mild weather — the intake air heater only aids cold starts, so you may notice harder starting and more smoke on cold mornings until it is fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Harder starting in cold weather
- Extra smoke and rough running on a cold start (diesel), clearing as it warms up
- Intake air heater stays cold / inoperative
Common causes
Most likely first
- Open circuit or broken wiring in the heater 'B' control circuitLikely
- Failed intake air heater relayCommon
- Faulty intake air heater elementCommon
- Corroded or loose connector, or a bad groundLess often
- Blown fuse or faulty PCM heater driverLess often
How to diagnose & fix
Work through it in order
- Scan and confirm the code, then inspect the heater 'B' wiring and connector for opens or corrosion.
- Check the heater relay and its fuse.
- Measure the heater element resistance and its supply voltage when commanded on.
- Repair wiring or replace the relay/element as needed.
- Clear the code and re-test, ideally on a cold start.
FAQ
Quick answers
Is it safe to drive with P2605?+
Yes. The intake air heater only helps the engine start and warm up in cold weather, so the vehicle drives normally — cold starts just take longer and may smoke more.
Can I just clear P2605?+
It will come back as soon as the module tests the heater circuit and finds it open. Repair the wiring, relay, or element to keep it from returning.
Related codes
Often seen with P2605
Read & clear P2605 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