Code Definition

B0174 — Output air temperature sensor signal out of range - sensor 1

System: Body  |  Type: Generic (OBD-II Standard)  |  Make: Generic

About B0174

B0174 is a generic (obd-ii standard) body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B0174 is stored, the module has detected a plausibility fault — the measured value is in the electrical range but is not consistent with expected operating behaviour; and a sensor-related fault — the reported value from the named sensor is out of spec.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

Because B0174 is a generic OBD-II code, its base definition is shared across manufacturers. The specific diagnostic steps, reference values, and repair procedures can vary by vehicle, and the TaT Diagnostic Assistant includes verified procedures submitted by working technicians.

Code Information

The Output Air Temperature Sensor (also called the discharge or duct sensor) is a thermistor mounted in the HVAC outlet duct that reports the temperature of the air leaving the heater/evaporator core to the HVAC control module. The module uses this feedback to confirm that the blend door, heater valve and A/C system are actually delivering the temperature commanded by the climate control strategy. DTC B0174 is set when the HVAC module sees the signal voltage from output air temperature sensor 1 fall outside its calibrated range, which usually means the thermistor has drifted, the harness is sh...

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