P2605 — Inlet air heater electrical circuit problem

The engine's inlet air heater circuit is open or has a fault, preventing proper operation. This heater helps warm the air entering the engine for better cold starts and emissions control. The code appears when the engine control unit detects no current or voltage where it expects it in the heater circuit.

Common causes

The cause is almost always one of a few things. Here they are — P2605 rarely comes from anything outside this list:

• Blown fuse or relay for inlet air heater
• Damaged wiring or connector in heater circuit
• Faulty inlet air heater element
• Defective engine control unit output
• Corroded or loose electrical connections

Where to start

In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:

1. Check and replace blown fuses or relays
2. Inspect and repair wiring and connectors
3. Test and replace inlet air heater element if faulty
4. Verify engine control unit output signals
5. Clear codes and test drive to confirm repair

That is what holds for P2605 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.