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P1112 OBD-II Trouble Code: Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage

Check Engine Light

P1112 definition

A P1112 trouble code is related to a vehicle’s intake air temperature sensor that measures the air entering the engine to adjust the fuel and cooling system in order to maintain a normal operating temperature threshold.

What the P1112 code means

P1112 is a OBD-II manufacturer-specific code for a voltage issue regarding the signal sent to the engine computer from the intake air temperature (IAT) sensor. The sensor contains a semiconductor device that changes resistance based on air temperatures coming into the intake manifold. The computer monitors voltage changes from the resistance of the sensor, and if the temperature is too high, the voltage signal will drop below the manufacturer’s threshold and trigger a P1112.

What causes the P1112 code?

The most common causes for a P1112 are:

  • Faulty intake air temperature sensor
  • Faulty intake air temperature sensor wiring/electrical connectors
  • Faulty engine computer computer

What are the symptoms of the P1112 code?

Symptoms of a bad or failing intake air temperature sensor range from a lack of power, trouble with cold starts, and decreased fuel economy. However, some P1112 codes may result in no noticeable symptoms other than a check engine light.

How does a mechanic diagnose the P1112 code?

Before troubleshooting with a OBD-II scanner, your mechanic will visually inspect the sensor and associated wiring, looking for any obvious damages. If the sensor and wiring are intact, they will then connect the scanner to the vehicle and monitor the reading from the IAT. At cold start, it should roughly match the coolant reading. Your mechanic will need to test drive the vehicle to get it up to operating temperature and ensure the IAT reading is indeed too high (low voltage).

Common mistakes when diagnosing the P1112 code

Because all P1XXX codes are manufacturer specific, it’s critical to have any code read by a professional-grade OBD-II scanner to ensure you’re fixing the correct problem. For example, a P1112 code in a Fiat is for the control fuel pressure system and one for a Daewoo is for the MAP sensor.

How serious is the P1112 code?

A faulty IAT sensor can cause a variety of unsavory driving characteristics, making it fairly serious for you to correct a P1112 as quickly as possible.

What repairs can fix the P1112 code?

The most common repairs for a P1112 are as follows:

Additional comments for consideration regarding the P1112 code

All P1112 codes that deal with the intake air temperature sensor are for Acura, Citroen/Peugeot, Ford, General Motors, Isuzu, Jaguar, Mazda, and Mercedes vehicles.

Need help with a P1112 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
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