Fault code P1112 – a step-by-step guide to diagnosing and fixing it

Error code P1112 is displayed and the check engine light is on - what does this mean?

The DTC P1112 is a manufacturer-specific fault code that is recognized by the OBD/EOBD diagnostics and indicates a problem with the intake air temperature sensor (IAT). This trouble code occurs when the engine control unit receives too low a voltage or an implausible value from the intake air temperature sensor.

What can cause this error code?

• Defective intake air temperature sensor (IAT)
• Damaged or corroded cable connections to the sensor
• Short circuit in the sensor cable
• Defective ground connection of the sensor
• Dirty or contaminated sensor
• Faulty plug connection on the sensor
• Defective engine control unit (rare)

What symptoms occur in parallel with error code P1112?

• Poor engine performance: The engine runs unevenly or has less power
• Increased fuel consumption: The vehicle consumes more fuel than usual
• Jerking when idling: The engine runs unevenly when stationary
• Starting problems: Difficulty starting the engine when cold
• Black smoke: Dark exhaust fumes from the exhaust pipe
• Check engine light: The check engine light is permanently illuminated

How can I fix the problem with fault code P1112?

• Repairing fault code P1112 requires a systematic approach to identify the cause.
• Sensor check and replacement: Check the intake air temperature sensor for correct resistance values using a multimeter and replace with an original part if defective
• Check the wiring: Check all cables and plug connections to the IAT sensor for damage, corrosion or loose contacts and repair them
• Sensor cleaning: Carefully clean the sensor with electronics cleaner if contamination is the cause
• Check the earth connection: Check the ground wire of the sensor for tight fit and freedom from corrosion and replace if necessary
• Diagnosis with OBD scanner: Read out live data from the sensor and compare with target values to identify the exact source of the fault