P0640
Intake Air Heater Control Circuit
P0640 is an OBD-II diagnostic trouble code meaning: Intake Air Heater Control Circuit. Common causes: intake air heater relay malfunction, blown heater circuit fuse. Estimated repair cost: $1–89.
Symptoms
- Check Engine light comes on
- Difficulty starting in cold weather
- White smoke from the exhaust pipe during cold start (diesel)
- Unstable idle when warming up
- Increased fuel consumption in winter
Causes
- Intake air heater relay malfunction
- Blown heater circuit fuse
- Open or short circuit in heater wiring
- Malfunction of the heating element (broken spiral)
- ECU malfunction (rare)
How to Fix
- Check the intake air heater circuit fuse
- Check heater relay (replace with a known good one)
- Check the heater supply voltage with the ignition on
- Measure the resistance of the heating element with a multimeter
- Inspect the heater wiring and connectors
- Replace the faulty component (relay, heating element)
Related codes
Error P0640 by Vehicle Brand
FAQ
What does the P0640 code mean?
P0640 is an OBD-II diagnostic trouble code that indicates: Intake Air Heater Control Circuit
What causes a P0640 error code?
The most common causes of P0640 include: Intake air heater relay malfunction; Blown heater circuit fuse; Open or short circuit in heater wiring; Malfunction of the heating element (broken spiral).
How do I fix a P0640 diagnostic trouble code?
To fix P0640: Check the intake air heater circuit fuse. Check heater relay (replace with a known good one). Check the heater supply voltage with the ignition on. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with P0640?
Yes, but get it checked soon
How much does it cost to fix P0640?
The estimated repair cost for P0640 is $1–89. Actual cost depends on your vehicle, location, and labor rates.
See also: Russian version · NationStat