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B1274 OBD-II Trouble Code: Servo Motor Potentiometer Vent Circuit Short to Battery

diagnostic check engine light

B1274 code definition

The B1274 trouble code detects an electrical error with the servo motor potentiometer vent circuit.

What the B1274 code means

The B1274 code is a standard OBD-II trouble code that notes an issue with the servo motor potentiometer vent circuit, which is a critical component in the heating, ventilation, and air conditioning (HVAC) system. The potentiometer helps control the vents by adjusting the voltage, which allows for the vents to be controlled on a varying scale. If a malfunction is detected in the servo motor potentiometer vent circuit, then the B1274 trouble code will be detected.

What causes the B1274 code?

A few different things can cause the B1274 code to be stored:

  • Faulty potentiometer
  • Malfunctioning servo motor
  • Short circuit
  • Damaged or defective electrical components
  • In rare cases, a malfunctioning climate control module, powertrain control module (PCM), or body control module

What are the symptoms of the B1274 code?

A vehicle with a detected B1274 code may have an illuminated check engine soon Warning Light, or a blinking A/C light on the climate controls. It is likely that the climate control system will not work properly, especially the vents.

How does a mechanic diagnose the B1274 code?

The B1274 code should be diagnosed with an OBD-II trouble code scanner. A trained technician will assess the code by looking at the scanner’s freeze frame data. The scanner will also be used to check for the presence of additional trouble codes, which, if found, will need to be addressed in the order that they show up in. The technician will then reset the trouble codes, restart the vehicle, and use the scanner to see if the B1274 code is still detected. If not, then the code was likely inaccurately detected, or the result of an intermittent issue.

If the code does remain detected, then the mechanic will visually inspect the electrical components in the climate control system. Any wires, connectors, or fuses that are damaged will need to be replaced, and then the circuit should be checked. If the issue remains unresolved, then the servo motor and potentiometer will require inspection.

When the mechanic repairs or replaces any component, the inspection will need to be paused while the codes are again reset, the vehicle restarted, and the B1274 code checked for. By doing this, the technician will know as soon as the issue is resolved.

Common mistakes when diagnosing the B1274 code?

The most commonly made mistake when diagnosing this code comes from the failure to fully comply with the OBD-II diagnosis protocol. The mechanic should abide by the diagnosis protocol at all times, as this guarantees that inspections and repairs will be both efficient and thorough.

It is common for properly working servo motors and potentiometers to be erroneously replaced because wires, fuses, connectors, and circuits were not first inspected.

How serious is the B1274 code?

The B1274 trouble code will not keep a car from being drivable, or present any drivability issues. However, this code may keep the climate control system from functioning properly. As with all trouble codes, an inspection should be scheduled when the code is detected.

What repairs can fix the B1274 code?

Some repairs for the B1274 trouble code are:

  • Potentiometer replacement
  • Servo motor replacement
  • Circuit replacement
  • Replacement 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 B1274 code

It is extremely uncommon for a PCM, body control module, or climate control module failure to be the cause of B1274 code. Mechanics should always inspect all potential causes of the code before assuming that there is control module failure. However, if either of these controllers does need to be replaced, then it will also need to be reprogrammed.

Need help with a B1274 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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