OBD Guide

P166C

Intake Air Heater Resistance

P166C is an OBD-II diagnostic trouble code meaning: Intake Air Heater Resistance. Common causes: intake air heater malfunction, open or short circuit in the heater circuit. Estimated repair cost: $17–56.

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

Symptoms

  • Difficulty starting the engine in cold weather
  • Unstable engine operation at idle
  • Increased fuel consumption
  • Check Engine Light Illuminates
  • Reduced engine power

Causes

  • Intake air heater malfunction
  • Open or short circuit in the heater circuit
  • Poor contact in circuit connectors
  • Faulty relay or control unit
  • Corroded contacts or damaged wiring harness

How to Fix

  1. Check the resistance of the intake air heater
  2. Inspect the heater circuit for damage
  3. Check contacts and connectors for corrosion
  4. Test the relay and control unit
  5. If necessary, replace the intake air heater

Related codes

FAQ

What does the P166C code mean?

P166C is an OBD-II diagnostic trouble code that indicates: Intake Air Heater Resistance

What causes a P166C error code?

The most common causes of P166C include: Intake air heater malfunction; Open or short circuit in the heater circuit; Poor contact in circuit connectors; Faulty relay or control unit.

How do I fix a P166C diagnostic trouble code?

To fix P166C: Check the resistance of the intake air heater. Inspect the heater circuit for damage. Check contacts and connectors for corrosion. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with P166C?

Yes, but get it checked soon

How much does it cost to fix P166C?

The estimated repair cost for P166C is $17–56. Actual cost depends on your vehicle, location, and labor rates.

See also: Russian version · NationStat