P0112: Intake Air Temperature Sensor 1 Circuit Low Bank 1

What does P0112 mean?

Intake air temperature sensor 1 is the first air temperature sensor in the intake path; depending on the vehicle it is built into the mass air flow sensor, mounted near the air filter or, on some naturally aspirated GM engines, fitted in the intake manifold. Most versions are NTC thermistors in a 5 V divider: the hotter the air, the lower the signal voltage. P0112 means the signal is below its valid range. With an NTC sensor that points to a short to ground in the signal wire or an internally shorted sensor, and the control module would read an implausibly hot value (GM about 150 °C). Documented limits: Ford petrol below 0.244 V for 5 s, Ford diesel below 0.10 V, GM below 62 ohms. The circuit is monitored continuously; GM needs two trips. Some systems then use the coolant temperature, capped at 40 °C, as a substitute and limit torque.

The code tells you which monitor failed, not which part is broken. Test before replacing parts.

Symptoms

• Check engine light on
• Usually hardly noticeable
• Retarded ignition, reduced power or torque limit on some systems
• Harder cold start possible

Common causes

• High Signal wire shorted to ground (chafed insulation)
• High Sensor shorted internally
• Medium Moisture or corrosion in the connector
• Low Engine control module faulty

Likelihood is a general estimate across vehicles; your make and model may differ.