If your vehicle's Check Engine Light (CEL) is on and you've scanned it for
trouble codes, you may have come across the code P0112. This code indicates that
the Engine Control Module (ECM) has detected a low input signal from the Intake
Air Temperature (IAT) sensor. In this guide, we'll explore the meaning of code
P0112, its symptoms, and how to troubleshoot the issue.
What does Code P0112 Mean?
The Intake Air Temperature (IAT) sensor measures the temperature of the air
entering the engine. This information is used by the Engine Control Module (ECM)
to adjust the air/fuel mixture and ignition timing for optimal engine
performance. Code P0112 indicates that the ECM has detected a low input signal
from the IAT sensor. This could be caused by a problem with the sensor itself,
the wiring, or the ECM.
Symptoms of Code P0112
The symptoms of code P0112 can vary depending on the vehicle's make and model,
but typically include:
Illuminated Check Engine Light
Poor fuel economy
Rough idling or stalling
Reduced engine power or acceleration
How to Troubleshoot Code P0112
Step 1: Check the IAT sensor wiring
The first step in troubleshooting code P0112 is to check the wiring between the
IAT sensor and the ECM. Look for any signs of damage, such as frayed or broken
wires, and ensure that all connections are clean and secure. If the wiring looks
good, move on to the next step.
Step 2: Test the IAT sensor
To test the IAT sensor, use a multimeter to measure its resistance at different
temperatures. Refer to your vehicle's service manual for the correct values. If
the readings are out of range, the sensor may be faulty and will need to be
Step 3: Check the ECM
If the IAT sensor and wiring are both in good condition, the problem may be with
the ECM itself. To test this, you'll need a diagnostic tool that can communicate
with the ECM. Use the tool to check for any fault codes related to the IAT
sensor or temperature sensor circuit. If no fault codes are present, try
resetting the ECM and see if the code returns.
Step 4: Replace the IAT sensor
If the IAT sensor is found to be faulty, it will need to be replaced. Refer to
your vehicle's service manual for the correct procedure. Once the new sensor is
installed, clear any fault codes and test drive the vehicle to ensure that the
CEL does not illuminate again.
Step 5: Replace the ECM
If the ECM is found to be faulty, it will need to be replaced. This is a more
complicated and expensive repair, so it's important to ensure that the ECM is
the actual cause of the problem before replacing it.
Code P0112 is an indication of a problem with the Intake Air Temperature (IAT)
sensor circuit. The symptoms of this code include poor fuel economy, rough
idling, and reduced engine power. To troubleshoot this code, start by checking
the IAT sensor wiring and testing the sensor itself. If both are in good
condition, check the ECM for any fault codes or reset it to see if the code
returns. If the sensor is faulty, replace it, and if the ECM is faulty, replace
it as a last resort. By following these steps, you should be able to resolve the
issue and get your vehicle running smoothly again.