B1250 — Air Temperature Internal Sensor Circuit Failure

What does OBD2 code B1250 mean?

B1250 — Air Temperature Internal Sensor Circuit Failure. A fault in the body electrical system. The car is usually drivable while you plan the repair. Typical causes: body control module (BCM) fault, blown fuse or failed relay, faulty switch, motor or actuator of the affected system.

Will B1250 clear itself?

Sometimes B1250 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

How much does it cost to fix B1250?

Repair wiring or connectors — $80–$250; Replace the switch or actuator — $120–$450; BCM repair or replacement — $300–$900. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

Is it safe to drive with B1250?

Usually safe to drive — body codes rarely affect drivability. Exceptions: exterior lighting and wipers in bad weather, and central locking faults that can leave the car unsecured.

How do I diagnose B1250 myself?

Start with a scan: confirm B1250, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the air temperature internal sensor circuit, and verify the suspect component against live data before buying parts.

Code B1250 points to a specific fault in your vehicle's body electrical system — the air temperature internal sensor circuit has failed. When the onboard computer repeatedly checks this sensor and consistently finds abnormal readings or a complete loss of signal, it stores this code in the body control module's memory and turns on the warning light.

This sensor feeds important climate data to your vehicle's body control module, which uses that information to manage cabin temperature-related functions. The ECU doesn't set B1250 after a single bad reading. Instead, it runs multiple verification cycles under specific conditions before confirming the fault. The freeze frame data stored alongside B1250 captures the exact circumstances — engine load, RPM, coolant temperature, vehicle speed — when the problem appeared. Reproducing those conditions during testing is essential for accurate diagnosis.

The code lives in the body electrical group, meaning the engine itself usually continues running normally. What changes is how your vehicle controls doors, windows, lighting, wipers, or other comfort features that rely on the BCM's interpretation of sensor data.

Symptoms

• The dashboard warning light remains illuminated
• The affected system — door locks, windows, interior lighting, or wipers — operates inconsistently or stops working entirely
• Climate-related controls may behave erratically
• Engine performance and drivability remain unaffected in most vehicles
• Some functions may work intermittently depending on temperature or vehicle movement

Causes

• Body control module (BCM) failure or internal fault
• Corroded, loose, or damaged connectors in the sensor circuit
• Wiring damage in door jambs, tailgate hinges, or other flex points exposed to moisture
• Failed air temperature internal sensor itself
• Blown fuse or malfunctioning relay in the affected circuit
• Broken or chafed wiring at stress points where movement occurs
• Poor electrical contact from water intrusion or oxidation

How to diagnose

1. Connect an OBD2 scanner and confirm B1250 is stored in the body control module. Save the freeze frame data — it shows the exact engine conditions (load, RPM, temperature, speed) when the fault was detected.
2. Check for related diagnostic trouble codes. Additional codes in the B-series often reveal whether the problem stems from the sensor, wiring, or module. Also search manufacturer technical service bulletins (TSB) for your make, model, and model year — many B0xxx codes have published factory fixes or software updates available through the manufacturer website or NHTSA database.
3. Visually inspect all wiring and connectors associated with the body electrical system. Look for damaged insulation, corrosion on pins, loose fits, or evidence of water entry.
4. Operate the affected function while monitoring switch and motor data in the live data stream. Watch for dropped signals or erratic values that confirm where the circuit is failing.
5. Pay close attention to flex points — door jambs, tailgate hinges, and any area where wires move repeatedly. These spots break first because of constant bending.
6. After any repairs, clear the code and complete a full drive cycle that includes the exact conditions from the freeze frame. If B1250 does not return, the repair is confirmed.

Repair options

• Wiring repair or connector replacement: $80–$250
• Air temperature internal sensor replacement: $120–$350
• Body control module (BCM) repair or replacement: $300–$900

How much does it cost to fix B1250?

Total repair cost for B1250 depends entirely on which component is responsible. Independent shop labor rates in the United States typically run $80–$250 for wiring or connector work, $120–$450 for sensor replacement including labor, and $300–$900 for BCM-level diagnosis, repair, or full replacement and reprogramming. The full range of scenarios spans $80 to $900. Always pursue an accurate diagnosis before purchasing expensive control modules — the priciest fix is rarely where you should start.

Can you drive with B1250?

Generally yes — B1250 rarely affects engine operation or safe drivability. The warning light may annoy you, but your vehicle should accelerate, brake, and steer normally. That said, exceptions matter: if the code affects exterior lighting or windshield wipers, reduced visibility in rain or darkness creates genuine hazard. Central locking faults could also leave your car unsecured. Use common sense based on which function is actually failing.

Related OBD2 codes

• B1200: Climate Control Pushbutton Circuit Failure
• B1201: Fuel Sender Circuit Failure
• B1202: Fuel Sender Circuit Open
• B1203: Fuel Sender Circuit Short To Battery
• B1204: Fuel Sender Circuit Short To Ground
• B1205: EIC Switch-1 Assembly Circuit Failure