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B1272 OBD-II Trouble Code: Servo Motor Potentiometer Vent Circuit Failure

diagnostic check engine light

B1272 code definition

The B1272 trouble code detects an error with the servo motor potentiometer vent circuit.

What the B1272 code means

The B1272 code is a standard OBD-II trouble code that identifies a problem with the servo motor potentiometer vent circuit, which is a key part of the heating, ventilation, and air conditioning (HVAC) system. The potentiometer is responsible for varying resistance to aid the operation of the cabin vents. If the climate control module, body control module, or powertrain control module (PCM) detects that the servo motor potentiometer is not operating properly, then the B1272 trouble code will be triggered

What causes the B1272 code?

A few different things can result in the B1272 trouble code being triggered: * Faulty potentiometer * Defective servo motor * Damaged electrical components in the system, including wires, connectors, fuses, and circuits * In rare cases, a defective PCM, body control module, or climate control module

What are the symptoms of the B1272 code?

When the B1272 trouble code is detected, the check engine soon Warning Light may illuminate, and the air conditioning light may flash. The climate control system will likely not operate properly, as it will possibly have ventilation problems.

How does a mechanic diagnose the B1272 code?

The B1272 code will be diagnosed with the help of a standard OBD-II trouble code scanner. A trained mechanic will view the freeze frame data from the scanner to assess the B1272 code, and search for the presence of additional trouble codes. If the technician finds that there are multiple trouble codes detected, then they will need to be inspected in the order in which they appear on the scanner. Next, the trouble codes will need to be reset, and the vehicle restarted, so the mechanic can check to see if the code remains detected. If it does not, then an intermittent error or an erroneous detection are likely to blame.

If the mechanic finds that the B1272 code is still present, then a visual inspection of the electrical components should be performed. Blown fuses, shorted wires, open connectors, and faulty circuits will all require replacement. The technician will then thoroughly inspect the potentiometer and the servo motor.

Any time a component is replaced or repaired, the technician will again reset the trouble codes, restart the vehicle, and check for the presence of the B1272 code. This will allow the mechanic to know as soon as the problem has been resolved.

Common mistakes when diagnosing the B1272 code

The most frequently made mistake when diagnosing this code comes from a failure to comply with the OBD-II diagnosis protocol. The protocol should always be followed step by step, as this helps avoid erroneous repairs, and ensure efficient inspections.

It is fairly common for electrical component failure to be overlooked, and fully functional potentiometers and servo motors to be unnecessarily replaced.

How serious is the B1272 code?

A vehicle with the B1272 trouble code will still be drivable. However, the climate control system will likely experience some problems. As is the case with all trouble codes, an inspection should be scheduled when the code is detected.

What repairs can fix the B1272 code?

Repairs for the B1272 trouble code include:

  • Potentiometer replacement
  • Servo motor replacement
  • Replacement or repair of the electrical components
  • In very rare cases, replacement of the PCM, body control module, or climate control module

Additional comments for consideration regarding the B1272 code

It is highly uncommon for the B1272 code to be caused by a faulty control module. Any possible causes for the code should be thoroughly inspected before any control module is condemned. If the PCM, body control module, or climate control module is found to be faulty, then it will need to be reprogrammed after being replaced.

Need help with a B1272 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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