Fuel & air metering · Powertrain · generic (SAE-defined)
P0112: Intake Air Temperature Sensor 1 Circuit Low (Bank 1)
P0112 means the intake air temperature (IAT) sensor signal voltage is lower than expected, which the engine computer interprets as an unrealistically hot air reading.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0112 sets
The intake air temperature (IAT) sensor is a thermistor whose resistance drops as air gets warmer, which lowers the signal voltage the powertrain control module (PCM) sees. If the voltage falls below the lowest plausible value for a set time, P0112 sets. A sensor shorted internally or a signal wire shorted to ground typically causes this. Voltage limits vary by manufacturer.
Common causes of P0112
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- IAT signal wire shorted to ground
- Internally shorted IAT sensor
- Faulty MAF sensor where the IAT is built in
- Water or corrosion in the connector
- PCM fault (rare)
P0112 symptoms
- Check engine light on
- Often no noticeable symptoms
- Possible hard cold starts
- Slight drop in fuel economy
How P0112 is diagnosed
- Scan for codes and check the IAT value in live data; a very high reading is typical
- Unplug the sensor; the reading should drop to a very cold value if the wiring is good
- Inspect the connector for moisture or corrosion
- Check the signal wire for a short to ground
- Measure sensor resistance against the factory chart
- Replace the sensor or repair wiring as indicated
Typical fixes for P0112
- Replace the IAT sensor
- Replace the MAF sensor if the IAT is integrated
- Repair a wire shorted to ground
- Clean or replace a corroded connector
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Manufacturer notes
Older definitions read "Intake Air Temperature Circuit Low Input". On many vehicles the IAT sensor is part of the MAF sensor; check factory service information.
Related codes & warning lights
P0112 FAQ
What does code P0112 mean?
P0112 means the intake air temperature (IAT) sensor signal voltage is lower than expected, which the engine computer interprets as an unrealistically hot air reading. The standard definition is "Intake Air Temperature Sensor 1 Circuit Low (Bank 1)."
Can I drive with a P0112 code?
Yes, it is generally safe to drive, since the engine computer falls back to a default air temperature. You may notice slightly worse fuel economy or cold-start behavior until it is fixed.
Why does live data show a very hot intake temperature with P0112?
A low signal voltage reads as high temperature, so a shorted sensor or grounded wire makes the PCM think the air is extremely hot.
How do I tell a bad sensor from a wiring short?
Unplug the sensor and watch the reading. If it changes to a very cold value, the wiring is likely fine and the sensor is suspect.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.