P2605
Intake Air Heater B Circuit / Open
The controller cannot drive the secondary intake air heater (heater grid B) used on diesel engines for cold-start support. The grid stays cold so cold-start emissions and white smoke increase.
- Check engine light: Yes
- Emissions related: No
- Repair difficulty: medium
Common causes
Ordered by how often each turns out to be the cause.
- Open heater grid elementCommon
- Failed heater relay or open coilPossible
Parts involved
- Intake Air Heater B
- Heater Relay
- Wiring Harness
P2605 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.