OBD Guide
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B12AF

Front Blower Motor Relay Drive Circuit Shorted To Battery Voltage

B12AF is an OBD-II diagnostic trouble code meaning: Front Blower Motor Relay Drive Circuit Shorted To Battery Voltage. Common causes: short circuit in wiring harness, faulty fan relay. Estimated repair cost: $33–111.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$33–111 (est.)

Symptoms

  • Heater fan runs constantly at maximum speed
  • Heater fan does not turn on
  • Unable to adjust fan speed

Causes

  • Short circuit in wiring harness
  • Faulty fan relay
  • Problems with the control unit
  • Corrosion or oxidation of contacts

How to Fix

  1. Check the integrity of the wiring harness
  2. Check the fan relay for short circuit
  3. Check contacts for corrosion
  4. Replace relay or wiring harness if necessary
  5. Check the control unit for errors

Related codes

B12AEB12B0

FAQ

What does the B12AF code mean?

B12AF is an OBD-II diagnostic trouble code that indicates: Front Blower Motor Relay Drive Circuit Shorted To Battery Voltage

What causes a B12AF error code?

The most common causes of B12AF include: Short circuit in wiring harness; Faulty fan relay; Problems with the control unit; Corrosion or oxidation of contacts.

How do I fix a B12AF diagnostic trouble code?

To fix B12AF: Check the integrity of the wiring harness. Check the fan relay for short circuit. Check contacts for corrosion. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B12AF?

Limited driving only, diagnose soon

How much does it cost to fix B12AF?

The estimated repair cost for B12AF is $33–111. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat