B12B2
Front Blower Motor PWM Drive Circuit Open or Shorted to Ground
B12B2 is an OBD-II diagnostic trouble code meaning: Front Blower Motor PWM Drive Circuit Open or Shorted to Ground. Common causes: open or short to ground in the wiring harness, fan motor malfunction. Estimated repair cost: $22–167.
Symptoms
- Heater fan does not turn on
- The fan only runs at one speed (usually maximum)
- Inability to adjust fan speed
Causes
- Open or short to ground in the wiring harness
- Fan motor malfunction
- Corrosion of contacts in connectors
- Problems with the resistor or fan control unit
- Malfunction of the climate control unit
How to Fix
- Visual inspection of the wiring harness and fan connectors
- Checking the resistance of the motor windings
- Diagnostics of the PWM output signal from the control unit
- Testing the fan operation when directly connected to the battery
- Replacement of faulty components (harness, motor, resistor, control unit)
Related codes
FAQ
What does the B12B2 code mean?
B12B2 is an OBD-II diagnostic trouble code that indicates: Front Blower Motor PWM Drive Circuit Open or Shorted to Ground
What causes a B12B2 error code?
The most common causes of B12B2 include: Open or short to ground in the wiring harness; Fan motor malfunction; Corrosion of contacts in connectors; Problems with the resistor or fan control unit.
How do I fix a B12B2 diagnostic trouble code?
To fix B12B2: Visual inspection of the wiring harness and fan connectors. Checking the resistance of the motor windings. Diagnostics of the PWM output signal from the control unit. For a complete diagnosis, use an OBD-II scanner.
Is it safe to drive with B12B2?
Limited driving only, diagnose soon
How much does it cost to fix B12B2?
The estimated repair cost for B12B2 is $22–167. Actual cost depends on your vehicle, location, and labor rates.
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