P0113
- Powertrain
- Generic (SAE)
- Emissions
Not urgent
The engine substitutes a default air temperature and generally runs normally. IAT trims spark timing and fuelling only modestly on most calibrations, so the practical effect is small. It rates above informational because a false extreme-cold reading can add fuel and let the calibration run more spark advance than the real intake temperature warrants — noticeable on some vehicles, and worth not leaving indefinitely in hot weather or under sustained load — and because it will fail an emissions inspection.
- Safe to drive
- Generally safe to drive. Expect minor cold-start or driveability quirks on some vehicles. If you hear pinging or knocking under load, especially in hot weather, ease off and get it repaired promptly; otherwise fix it before an emissions test.
Intake Air Temperature Sensor High Input
The intake air temperature signal is stuck at high voltage, which the computer reads as an impossibly cold intake — often displayed as around -40 degrees. That is the electrical signature of a broken connection, not a real temperature.
The IAT sensor is a negative temperature coefficient thermistor wired in a divider with a pull-up resistor inside the module, usually referenced to 5 volts. Colder air means higher sensor resistance, which means higher signal voltage. An open circuit anywhere in the sensor, the signal wire, or the sensor ground lets the signal float to the pull-up voltage, which the module translates to the bottom of its temperature table. On many vehicles the IAT element is built into the mass air flow sensor housing rather than being a separate part, so an unplugged or failed MAF sensor can set P0113 along with MAF codes.
How the car detected itThe module compares IAT signal voltage against a calibrated high threshold — commonly somewhere above 4.5 volts, though the exact figure is vehicle-specific — and sets the code if it stays there for a defined period with the engine running. Separately, most strategies run a soak rationality check comparing intake air temperature against engine coolant temperature on an engine that has sat overnight; a large disagreement generally sets an IAT range/performance code such as P0111 rather than P0113, but it remains one of the fastest ways to confirm the sensor is lying.
A trouble code records what a control module measured. It does not identify which part failed. Test before replacing anything.
- Safe to drive
- Generally safe to drive. Expect minor cold-start or driveability quirks on some vehicles. If you hear pinging or knocking under load, especially in hot weather, ease off and get it repaired promptly; otherwise fix it before an emissions test.
- Urgency
- Not urgent
- Will it pass emissions
- No
- If ignored
- The light stays on, readiness stays incomplete, and the vehicle fails inspection. Depending on the calibration, a permanent false cold reading can add fuel and allow more spark advance than conditions warrant, costing some fuel economy and occasionally producing a slightly rough or sluggish feel, with some added detonation sensitivity on a hot day under load. It will not damage anything quickly, but a stored code means the light is already on, so a new fault gives you no fresh warning — that is the real cost of leaving it.
- Check engine light
- Solid
- Clearing the light
- A completed drive cycle is normally required before the monitor re-runs and the light can clear.
These are the causes this code can have. For the order to work through them in, see what to check first.
| # | Cause | How often | Component |
|---|---|---|---|
| 1 | Open circuit in sensor or wiring | Very common | — |
| 2 | Corroded sensor connector | Common | — |
Ordering reflects how often each cause is responsible in general, not a probability for your vehicle. Confirm by testing.
In order. Each of these is cheaper or faster than what follows it, and each one can make the rest unnecessary.
Whether IAT is built into the MAF sensor on this vehicle
On many vehicles there is no standalone IAT sensor to replace. If IAT lives inside the MAF, an unplugged or damaged MAF connector explains the whole code, and buying a separate IAT sensor is impossible.
The IAT reading in live data
If it shows the bottom of the table — commonly around -40 — that is the open-circuit default, not a measurement. Recognising it as a default rather than a reading saves you from chasing a phantom cold-intake problem.
IAT compared against coolant temperature after an overnight soak
On an engine that has sat all night the two should read within a few degrees of each other. A large split confirms the sensor or its circuit rather than genuine conditions, and it takes ten seconds on a scan tool.
The sensor connector
A pin pushed back in the housing, corroded terminals, or a connector not fully latched produces the open circuit this code describes and costs nothing to inspect.
Read live data for IAT, ECT, and MAF together
Tools OBD-II scan tool with live data
Note the IAT value and whether it is at the table floor. Compare against coolant temperature on a cold engine. Check whether MAF codes are also present, which points toward an integrated sensor or a shared connector.
ExpectedOn a cold soaked engine, IAT within a few degrees of ECT
Inspect the sensor and its connector
Tools Light, pick set, terminal probes
Unlatch the connector and examine both halves. Look for green corrosion, oil or coolant intrusion, a spread female terminal, or a pin backed out of its lock. Check the pigtail where it flexes.
ExpectedClean, tight terminals, connector fully latched
Run the jumper test
Tools Jumper wire, scan tool, wiring diagram
This is the single most efficient test for this code. Unplug the sensor and connect the two sensor pins together with a jumper wire while watching live data. Shorting the circuit should drive the signal toward zero volts and make the scan tool report the top of the temperature table. Which pins are signal and ground varies by manufacturer — use the wiring diagram.
ExpectedIAT jumps to a very high displayed temperature, confirming wiring and module are good
If the jumper changes nothing, test the circuit itself
Tools Multimeter, wiring diagram
An unchanged reading means the fault is in the harness or module, not the sensor. Key on, measure voltage at the signal pin with the sensor unplugged — you should see the module's reference voltage, typically near 5 volts. No voltage means an open signal wire or a module supply problem.
ExpectedReference voltage present at the signal pin
Verify the sensor ground path
Tools Multimeter
Check continuity from the sensor ground pin back to the module's sensor ground. An open ground gives exactly the same high-voltage signature as an open signal wire, and is easy to overlook.
ExpectedContinuity with essentially no resistance
Measure sensor resistance against the temperature table
Tools Multimeter, thermometer, heat source, service data
With the sensor out and at a known temperature, measure across it and compare against the manufacturer's temperature-resistance table. Resistance should fall as the sensor warms — warm it gently with a heat gun and watch the value drop smoothly.
ExpectedResistance within the table's range and changing smoothly with temperature
Hunt for an intermittent open in the harness
Tools Scan tool with graphing, wiring diagram
If everything tests good statically, the fault is likely intermittent. Wiggle the harness from the sensor back through the loom while watching live data, paying attention to where the harness passes near heat sources or moves with the engine.
ExpectedIAT reading stays stable through the wiggle
Confirm the repair over a cold start and a warm-up
Tools Scan tool
Clear codes and verify IAT tracks ambient temperature at a cold start, then climbs sensibly as underhood heat builds. A sensor reading plausibly at both ends of a warm-up is a confirmed repair.
ExpectedIAT matches ambient when cold, rises during driving, no code return
| Repair | Only after you confirm | Typical cost | Who |
|---|---|---|---|
| Replace the intake air temperature sensor | Jumper test restores a plausible reading, proving the wiring and module are good, and the sensor measures open or out of table | $60–$220 | DIY |
| Replace the combined MAF/IAT sensor on integrated designs | Same jumper-test confirmation on a vehicle where IAT is not separately serviceable | $150–$500 | DIY |
| Repair an open signal wire or sensor ground | Jumper test produces no change, plus a confirmed break in continuity or missing reference voltage at the sensor connector | $110–$380 | DIY |
| Repair or replace the sensor connector | Corroded, spread, or backed-out terminals, or a reading that corrects when the connector is manipulated | $80–$280 | DIY |
A standalone IAT sensor is one of the cheaper sensors on the vehicle and is often a five-minute job. The cost swings when the element is integrated into the MAF housing or into the intake manifold pressure sensor, or when the actual fault is an intermittent harness break, where diagnostic time dominates the bill.
- Replacing the sensor without doing the jumper test. That one test separates a failed sensor from an open harness in under a minute, and the harness is at fault often enough to matter.
- Not realising IAT is integrated into the MAF sensor on many vehicles, then hunting for a standalone part that does not exist.
- Confusing P0113 with P0112. P0113 is high voltage and reads implausibly cold; P0112 is low voltage and reads implausibly hot. They point in opposite directions.
- Treating the -40 reading as a real measurement and chasing an intake problem that is not there.
- Overlooking the sensor ground. An open ground produces the identical high-voltage symptom as an open signal wire.
- Intake Air Temperature Sensor
- Intake Air Temperature Sensor Wiring
- Definition
- Generic code set (SAE J2012 / ISO 15031-6) via the OBDexopen database, dedicated to the public domain under CC0-1.0.
- Diagnostic guidance
- Written and reviewed in-house. See our editorial policy.
- Review status
- Reviewed
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