OBD Guide
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P166B

Intake Air Heater Over Temperature

P166B is an OBD-II diagnostic trouble code meaning: Intake Air Heater Over Temperature. Common causes: heating element malfunction, heater control circuit problems. Estimated repair cost: $17–56.

Severity
⚠️ Medium
Can you drive?
Yes, but get it checked soon
Approx. repair cost
$17–56 (est.)

Symptoms

  • Check Engine light comes on
  • Reduced engine power in cold weather
  • Increased fuel consumption
  • Unstable engine idling
  • Possible starting problems in cold weather

Causes

  • Heating element malfunction
  • Heater control circuit problems
  • Heater relay malfunction
  • Open or short circuit in wiring harness
  • Intake air temperature sensor malfunction

How to Fix

  1. Check the integrity of the heating element
  2. Check voltage and resistance in control circuit
  3. Check the operation of the heater relay
  4. Inspect the wiring harness for damage
  5. Check the intake air temperature sensor readings

Related codes

P166AP166CP166D

FAQ

What does the P166B code mean?

P166B is an OBD-II diagnostic trouble code that indicates: Intake Air Heater Over Temperature

What causes a P166B error code?

The most common causes of P166B include: Heating element malfunction; Heater control circuit problems; Heater relay malfunction; Open or short circuit in wiring harness.

How do I fix a P166B diagnostic trouble code?

To fix P166B: Check the integrity of the heating element. Check voltage and resistance in control circuit. Check the operation of the heater relay. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P166B?

Yes, but get it checked soon

How much does it cost to fix P166B?

The estimated repair cost for P166B is $17–56. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat