P2604 to P2609, P2029 and P2030: intake air heaters and fuel-fired heater
Diesel intake air heater A or B is out of range or performs poorly, the intake air heater system has a fault, or the fuel-fired auxiliary heater is disabled or has a fault.
SeverityLowLittle risk to the car, but the fault stays until it is repaired.
Can you keep driving?Safe to drive, book a checkWhat does P2604 mean?
Where P0540 to P0543 cover the first intake air heater's circuit, these codes add the second heater and the performance of the whole system, which helps a diesel start and run cleanly in the cold. A fuel-fired heater burns a little diesel to warm the coolant, and so the cabin and the engine, before or soon after starting; it is common on diesels sold in cold countries. These faults make cold starts and the first minutes of driving harder, but do not affect a warm engine.
What causes P2604?
- A burnt-out heater grid or a failed heater relay
- A corroded heavy cable terminal at the heater
- A fuel-fired heater that has sooted up or lost its fuel supply
- A fuel-fired heater disabled because the tank is low
- A damaged control wire
What to check first for P2604
- Note whether cold starts have become harder or smokier
- Check the heater relay and the heavy cable terminals
- For the fuel-fired heater, check that there is enough fuel in the tank
- Have the heater's own fault memory read, for fuel-fired heaters
Can you drive with P2604?
You can drive safely. Cold starts may be harder and the cabin slower to warm up, so have it repaired before the cold season.
In states with an OBD-II emissions inspection, a car with the check engine light on fails the test until the fault is fixed.
Codes on this page
- P2029Fuel Fired Heater Disabled
- P2030Fuel Fired Heater Performance
- P2604Intake Air Heater "A" Circuit Range/Performance
- P2605Intake Air Heater "A" Circuit/Open
- P2606Intake Air Heater "B" Circuit Range/Performance
- P2607Intake Air Heater "B" Circuit Low
- P2608Intake Air Heater "B" Circuit High
- P2609Intake Air Heater System Performance
Related codes
Checked on · Rafael Soares
These are the generic meanings every manufacturer shares. Each brand adds its own detail, so your car's handbook, its service information and a qualified mechanic have the last word. OdoKeep has no connection with any manufacturer, and the app does not read codes from the car.
