Intake Air Temperature (IAT) Sensor
What it is
The intake air temperature sensor measures the temperature of the air entering the engine. It is often built into the MAF sensor or mounted in the intake duct.
What it does
Air density changes with temperature, so the computer uses IAT to fine-tune fuelling and timing. A faulty IAT can cause poor economy, hard starting and hesitation, and sets P0112/P0113.
Symptoms of failure
- Codes P0112 (low) or P0113 (high)
- Poor fuel economy
- Hard starting in heat or cold
- Hesitation or rough running
- Black smoke (over-fuelling)
Common fault codes
Which vehicles need it
Most fuel-injected engines; frequently integrated into the MAF sensor on Ford, VW/Audi and others.
Replacement cost
| DIY (part only) | $10–$60 |
|---|---|
| At a shop (parts + labor) | $90–$200 |
| Replacement interval | No set interval — replace on failure (or clean if integrated in a dirty MAF). |
| DIY difficulty | Easy (DIY) — usually one connector; replace the MAF if it is the integrated type |
| Recommended brands | Standard Motor Products, Bosch, Delphi, ACDelco |
Where to buy the part
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Frequently asked questions
Is the IAT sensor part of the MAF sensor?
On many cars, yes — the IAT element is built into the mass air flow sensor. If your IAT code will not clear, you may need to clean or replace the whole MAF assembly.
Can a dirty air filter affect the IAT sensor?
It can contribute, since a clogged or oily intake can foul the sensor element. Keep the air filter clean and the IAT reading stays accurate.