P2606 moderate

Intake Air Heater A Circuit High

The P2606 code means the vehicle's onboard diagnostic system has detected: Intake Air Heater A Circuit High. This is a moderate severity code.

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Keep driving?
Yes, but fix soon
DIY difficulty
moderate
Estimated cost
$150 - $500 (parts and labor)
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Common Symptoms

  • Intake air heater staying on too long
  • Higher than normal intake air temperature
  • Possible detonation or knocking
  • Check engine light on

Probable Causes (Ranked by Likelihood)

  • Short to voltage in heater control circuit Very High
  • Air heater relay stuck on High
  • ECM heater timer malfunction Moderate
  • Wiring harness damage near exhaust manifold Low

Step-by-Step Diagnostic Procedure

  1. Check if heater stays powered after warm-up

  2. Test air heater relay for stuck contacts

  3. Monitor ECM heater command duration

  4. Inspect wiring near hot exhaust components

Frequently Asked Questions

Can an always-on air heater cause engine damage?

Over-heated intake air can cause pre-ignition or detonation in diesel engines, potentially damaging pistons and cylinders over time.

How do I know if the heater relay is stuck?

Check for voltage at the heater with the engine fully warm. At operating temperature, the heater should be off. If voltage is present, the relay is likely stuck.

Will P2606 affect fuel economy?

Slightly. Over-heated intake air reduces air density, which can affect combustion efficiency and increase fuel consumption.

Sources

This page is built from documented references. Verify against your own service info before repair work.

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