Intake Air Temperature Sensor Circuit High Input
IAT signal voltage too high — sensor reading impossibly cold. Open wire or failed sensor.
What it means (plain English)
Same thermistor concept as ECT, just measuring incoming air temperature. P0113 means the signal is pinned at ~5 V, which would mean the air is colder than physically possible (often -40°F). That happens when the signal wire goes open — the pullup resistor in the PCM holds it at 5 V because nothing is pulling it down.
What the computer is actually seeing
IAT signal above maximum threshold (typically >4.8 V) for sustained time.
What a healthy reading looks like
IAT signal should track within a few degrees of ambient on a cold start. After heat-soak in summer it can read 140–180°F under the hood.
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 1Verify connector is plugged in and clean.
- 2Jumper the signal pin to ground with key on. Voltage should drop and IAT reading should pin to ~250°F. If it does — sensor or wire is open between signal and PCM.
- 3If jumpering does nothing — open ground wire or PCM issue.
Common causes
- Open signal or ground wire to IAT (often built into MAF on modern vehicles)
- Failed IAT sensor (open internally)
- Disconnected MAF/IAT connector
Typical repair cost
$30–$200 (often replaced as part of MAF).
Related codes
Frequently asked questions
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