B1250 code definition
The B1250 trouble code detects an error with the air temperature internal sensor.
What the B1250 code means
The B1250 code is a generic OBD-II trouble code that notes a circuit failure with the air temperature internal sensor. The air temperature internal sensor records the temperature in the interior of the vehicle, and relays the information to the climate control module. This allows the climate control module to accurately control the automatic climate control system. When the climate control module notes a malfunction in the air temperature internal sensor circuit, or fails to receive a reading from the sensor, then the B1250 trouble code will be stored.
What causes the B1250 code?
The B1250 trouble code is usually caused by:
a defective air temperature internal sensor
in rare cases, a result of a malfunctioning climate control module, powertrain control module (PCM), or body control module
What are the symptoms of the B1250 code?
The B1250 trouble code will usually be accompanied by an illuminated check engine soon Warning Light on the vehicle’s instrument panel. It is also likely that the automatic climate control system will not work.
How does a mechanic diagnose the B1250 code?
The B1250 code will be diagnosed with the help of an OBD-II trouble code scanner. A reputable technician can use the scanner to view the freeze frame data and assess the code. The scanner will also be used to check for the presence of any other trouble codes that have been detected. If the mechanic finds that there are multiple trouble codes present, then they will need to be inspected and repaired in the order in which they occur on the scanner. The technician will then need to reset the trouble codes, restart the vehicle, and look to see if the code still remains detected. If not, then a faulty trigger, or an intermittent error should be suspected.
If the B1250 trouble code remains detected, then the mechanic should begin with a visual inspection of all of the electrical components. Blown fuses, corroded connectors, and shorted wires will need to be replaced. If the technician notices that the damage is caused by something, such as an oil leakage, then a more thorough inspection will need to take place, as there may be a more critical component failure that needs to be addressed. If all of the electrical components are in working order, then a defective air temperature internal sensor should be suspected.
After any replacements are made, the mechanic will need to again reset the codes, restart the vehicle, and check for the presence of the B1250 code. This will help the technician be alerted as soon as the issue is resolved.
Common mistakes when diagnosing the B1250 code
The most frequently made error when diagnosing this code comes from not complying with the OBD-II trouble code diagnosis protocol. The protocol should be followed step by step at all times, as this ensures a thorough diagnosis, and no erroneous repairs.
Functional air temperature internal sensors are frequently and unnecessarily replaced, when the only issue is a damaged wire, connector, or fuse.
How serious is the B1250 code?
The B1250 trouble code will not keep a vehicle from being drivable, though it may keep the automatic climate control system from working. As with all trouble codes, it’s a good idea to have the vehicle inspected and repaired as soon as the code is detected.
What repairs can fix the B1250 code?
Repairs for the B1250 trouble code include:
Replacement of electrical components in the system
In rare cases, replacement of the PCM, climate control module, or body control module
Additional comments for consideration regarding the B1250 code
It is very rare for the B1250 code to signal a control module failure, so all possible causes should be thoroughly inspected before the PCM, climate control module, or body control module is condemned. If a control module is replaced, it will need to be reprogrammed.
Need help with a B1250 code?
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This article originally appeared on YourMechanic.com as B1250 OBD-II Trouble Code: Air Temperature Internal Sensor Circuit Failure and was authored by Brady Klopfer.