What Does P0112 Mean?
The ECM has detected that the Intake Air Temperature (IAT) sensor on bank 1 is producing a voltage signal that is lower than the expected minimum threshold. Since the IAT sensor is a negative temperature coefficient (NTC) thermistor, low voltage corresponds to an implausibly high temperature reading — often over 280°F (138°C). This is almost always a circuit issue rather than actual extreme intake air temperatures. The ECM will use a default value, causing slightly degraded performance.
Common Causes
35%
Shorted IAT sensor (internal thermistor shorted, reading near zero ohms)
30%
IAT sensor signal wire shorted to ground in the harness
20%
Water intrusion or corrosion in the IAT connector causing signal to ground short
10%
Damaged or pinched IAT harness near engine or body ground points
5%
ECM internal pull-down fault on IAT input
Diagnostic Steps
1
Check live data — if the IAT reads an extreme high temperature (250°F+) when the actual intake air is cool, confirm the low-input circuit condition.
2
Disconnect the IAT sensor connector. If the voltage at the ECM side jumps to approximately 5V (high input / -40°F reading), the wiring is intact and the sensor is shorted internally. Replace the sensor.
3
If the voltage remains low with the sensor disconnected, check the signal wire for a short to ground — measure resistance from the signal wire to chassis ground at the ECM connector (should read open/infinite).
4
Inspect the IAT sensor connector and harness routing for chafing against metal edges, water pooling, or heat damage that could cause insulation breakdown.
5
Measure the IAT sensor resistance directly across its terminals. At room temperature (68°F/20°C), it should read approximately 2.0-3.0 kOhms. A reading near zero ohms confirms a shorted sensor.
Estimated Repair Cost
$15 - $125
Parts + labor, varies by vehicle and location
The ECM has detected that the Intake Air Temperature (IAT) sensor on bank 1 is producing a voltage signal that is lower than the expected minimum threshold. Since the IAT sensor is a negative temperature coefficient (NTC) thermistor, low voltage corresponds to an implausibly high temperature reading...
The most common cause of P0112 (Intake Air Temperature Circuit Low Input Bank 1) is: Shorted IAT sensor (internal thermistor shorted, reading near zero ohms)
Typical repair costs for P0112 range from $15 to $125, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Safe to drive. The ECM defaults to a substitute IAT value. The engine may run slightly leaner or richer than optimal depending on the default strategy, but there is no safety risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0112 to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel / Air Metering
Difficulty
Type
Generic (SAE)
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