P0112: Intake Air Temperature Sensor 1 Circuit Low

What does P0112 mean?

The IAT sensor measures the temperature of the air entering the engine. The computer uses it, with the airflow or pressure reading, to work out air density and fuel delivery. P0112 is a circuit code: the signal is lower than the sensor should produce.

When the signal is out of range, the computer typically ignores it and uses a substitute value. That keeps the engine running but can make starting and fuel economy worse.

Common symptoms

• Check engine light on
• Hard starting in some cases
• Lower fuel economy
• In many cases no obvious symptoms

Common causes

The causes below are the ones commonly seen with P0112. The actual cause can vary by vehicle, engine and mileage, so treat this list as a starting point, not a diagnosis.

• A faulty intake air temperature sensor
• Damaged wiring or a short in the IAT sensor circuit
• A loose, damaged or corroded IAT sensor connector

What to check with a scanner

• Compare the intake air temperature in Live data with the outside temperature after the car has sat overnight. They should be close.
• Look at the coolant temperature on a cold engine too. The two readings should be similar before the first start.
• Inspect the sensor connector, which is often built into the airflow sensor or air box.
• Clear the code and see if it returns.

How to read and clear P0112 with OBD Master Pro

1. Plug in your adapter. Connect a generic ELM327 (or ELM329) OBD2 adapter to the diagnostic port, usually under the dashboard on the driver's side. Bluetooth Classic, Bluetooth LE, Wi-Fi and USB OTG adapters are supported.
2. Switch the ignition on. Turn the key to ON or start the engine, depending on your car.
3. Connect in OBD Master Pro. Open the app, go to Connection and pick your adapter. Classic Bluetooth adapters connect from the Bluetooth tab, Bluetooth LE adapters from the BLE tab with no pairing needed. Use the generic OBD2 / EOBD profile or your car's brand profile.
4. Read the codes. Open the fault codes screen to see stored, pending and permanent codes. Confirm P0112 is listed and note any other codes, since they often explain the cause.
5. Check the details. Look at freeze frame data, Live data and, where your car supports it, Mode 06 test results (see the checks above).
6. Fix, then clear. After the repair, clear the codes to turn off the check engine light. Clearing also resets the emissions readiness monitors, so drive normally and check the readiness screen before any inspection. Permanent codes cannot be erased with a scan tool; they clear on their own once the car's self test passes.

Tip: you can also look up P0112 and other codes in the app's DTC search without connecting to a car. If your adapter will not connect, use Connection > Share connection log and email it to support. Many cheap ELM327 clones only handle basic engine OBD2, which is all you need for P0112.

When to see a mechanic

Get professional help if any of these apply:

• The reading in Live data is clearly wrong and the connector looks fine
• Wiring needs to be tested with a meter
• The engine is hard to start

If you are unsure, a qualified technician can confirm the cause with tests such as smoke testing, pressure testing or scope readings. Clearing a code does not repair the fault.

Related trouble codes

See all OBD2 trouble code guides

Related guides

Check engine light on: what to do · How to read an OBD2 code (P, B, C, U) · Stored, pending and permanent codes and freeze frame · OBD2 readiness monitors explained · OBD2 glossary · OBD2 by car brand