P0640
Intake Air Heater Control Circuit
A general circuit fault on the intake air heater control - the ECU cannot drive the grid heater at cold-start.
- Check engine light: Yes
- Emissions related: Yes
- Repair difficulty: medium
Symptoms
- Check engine light on
- Possible limp mode or no-start
- Multiple follow-up faults across modules
- Reset/relearn may be needed after repair
Common causes
Ordered by how often each turns out to be the cause.
- Open in heater or wiringCommon
Parts involved
- Intake Air Heater
P0640 is a generic OBD-II code defined by SAE J2012. Exact wording and diagnostic procedure vary by manufacturer and model. Code definitions are drawn from the public-domain OBDex dataset; the workshop notes are our own.