OBD Guide
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B1966

A/C Post Heater Sensor Circuit Failure

B1966 is an OBD-II diagnostic trouble code meaning: A/C Post Heater Sensor Circuit Failure. Common causes: post-heater sensor malfunction, open or short circuit in wiring harness. Estimated repair cost: $56–167.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$56–167 (est.)

Symptoms

  • Incorrect operation of the climate control system
  • No air heating after switching on
  • Unstable temperature in the cabin

Causes

  • Post-heater sensor malfunction
  • Open or short circuit in wiring harness
  • Problems with the climate control unit
  • Poor contact in connectors

How to Fix

  1. Check the integrity of the sensor wiring harness
  2. Measure sensor resistance
  3. Check contacts in connectors
  4. Replace sensor if necessary
  5. Scan the system for other errors

Related codes

B1965B1967B1968

FAQ

What does the B1966 code mean?

B1966 is an OBD-II diagnostic trouble code that indicates: A/C Post Heater Sensor Circuit Failure

What causes a B1966 error code?

The most common causes of B1966 include: Post-heater sensor malfunction; Open or short circuit in wiring harness; Problems with the climate control unit; Poor contact in connectors.

How do I fix a B1966 diagnostic trouble code?

To fix B1966: Check the integrity of the sensor wiring harness. Measure sensor resistance. Check contacts in connectors. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1966?

Limited driving only, diagnose soon

How much does it cost to fix B1966?

The estimated repair cost for B1966 is $56–167. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat