P0113

00:00What this code means

Code P0113. Intake Air Temperature Sensor 1 Circuit High Input.

In plain English: the engine computer saw intake-air-temperature sensor 1 voltage too high, which usually appears as impossibly cold air on scan data; high input does not mean the incoming air is too hot.

A short, gentle trip is usually possible if the engine starts and runs normally, but fuel mixture, ignition timing, boost and emissions controls may use substitute values. Stop and arrange service if the engine stalls, runs severely rich, produces heavy smoke, loses substantial power or sets another warning that changes the safety picture.

00:41How the test actually works

Here's what your engine computer is actually measuring.

Most intake-air-temperature sensors are negative-temperature-coefficient thermistors. The engine computer supplies a pull-up voltage and watches the signal through the sensor to its return circuit. Cold air raises thermistor resistance and signal voltage; warm air lowers resistance and voltage. The computer converts that voltage into a temperature used for fueling, timing, boost and emissions calculations.

P0113 sets when the IAT 1 signal remains above the calibrated electrical limit, or the calculated temperature remains below the allowed minimum, for the required time. Manufacturer examples include more than 4.47 volts or a calculated temperature below roughly minus 45 degrees Celsius, but those are examples rather than universal specifications. An unplugged sensor, open signal or open return can all pull the reading high.

So the code is not a part failure report. It's a performance measurement that came back under spec.

01:48Symptoms

What you'll usually notice, beyond the light itself.

Check-engine light with an implausibly cold IAT reading. The scan value may be near the tool's lower limit even when the engine bay and outside air are warm.

Hard starting, rough cold operation or hesitation. A false cold value can alter commanded fuel, spark and airflow strategies.

Reduced fuel economy or a fuel smell. Some gasoline calibrations enrich the mixture when the computer believes the intake air is extremely cold.

Reduced power or changed boost and emissions behavior. Turbocharged and diesel applications may substitute values or limit a temperature-dependent control.

Sometimes no symptom beyond the warning light. A plausible substitute value can hide the failed input during ordinary driving.

02:44Most likely causes, ranked

Now the part you came for: what actually causes this, ranked by how often it turns out to be the culprit.

28 percent of the time, it's this: Loose connector, pushed-out pin or spread terminal. A terminal that looks connected can lose the signal or sensor-return contact when vibration or wire strain moves it.

24 percent of the time, it's this: Open or broken wire in the IAT signal or return circuit. Harness rub-through, a broken conductor or a poor splice can leave the pull-up voltage near its maximum.

22 percent of the time, it's this: Internally open IAT thermistor or integrated sensor. The temperature element may fail by itself even when it shares a housing with the MAF, MAP or pressure sensor.

11 percent of the time, it's this: Corrosion, moisture or high resistance at a connector or ground. Resistance added to the return side can bias the signal colder and may become intermittent with heat or humidity.

9 percent of the time, it's this: Signal wire shorted to reference voltage or another powered circuit. A melted or pinched harness can place excessive voltage on the input even with a working sensor.

6 percent of the time, it's this: PCM calibration, connector or input fault. This is the final branch after the temperature element and complete circuit have been proven at the controller.

Notice that the most expensive repair is not the most likely one. That matters, because the cheap checks come first.

04:21The measurement that decides it

This is the single measurement that tells you whether you need the expensive part or the cheap one.

After the vehicle has sat long enough to equalize, turn the key on before starting and compare intake-air temperature with ambient air and engine coolant temperature. This graph is illustrative; use the vehicle's specified soak time and allowable difference.

A known-good IAT begins near the other cold-soaked temperature readings, then rises gradually from engine-bay heat and airflow after startup. The values do not need to be identical, but they should make physical sense.

The P0113 trace stays near an extreme cold default while ambient and coolant are ordinary. An intermittent open can jump instantly between a believable value and the cold limit when the connector or harness moves.

If scan data is implausibly cold, inspect the connector before unplugging it, then use the factory-approved resistor, simulator or back-probe test. If the displayed temperature responds, the sensor or its connection is suspect; if it does not, trace the signal and return to the computer.

05:29Diagnostic order

So here is the order to actually test this, cheapest and most likely first.

Step 1. After a proper cold soak, is IAT 1 implausibly colder than ambient and coolant? Save every code and freeze frame before clearing anything. Compare all temperatures key-on engine-off and confirm the scan tool is showing the correct IAT parameter; an ordinary reading now points toward an intermittent fault or enabling condition.

Step 2. Is the correct sensor fully connected with clean, tight and seated terminals? Inspect before disconnecting so a pushed-out pin is not accidentally reseated. Check connector locks, wire strain, corrosion and harness routing, especially when IAT is integrated into another airflow or pressure sensor.

Step 3. Does scan temperature respond correctly to the approved resistor or simulator test? Use only the factory test value and pinout. Never short a five-volt reference directly to ground. If the displayed temperature moves to the specified value, the computer and most of the harness can see a valid resistance.

Step 4. Do signal, return, continuity and short-to-voltage tests meet specification? Test both conductors end to end and under light harness movement, then load-test the return where the procedure requires it. Check shared references before condemning an integrated MAF, MAP or pressure sensor.

Step 5. Does the correct signal voltage and temperature relationship reach the PCM pins? Prove the signal at the controller under the same condition. If it is correct there but scan data remains wrong, verify connector fit, grounds and software before considering the rare PCM input fault.

Start with the impossible temperature, preserve the connector evidence, and prove where the pull-up circuit opens before replacing an integrated sensor.

07:32Repair costs

What this costs to put right, in US dollars, parts and labor.

Connector terminal or pigtail repair: 10 to 180 dollars in parts, plus about 1.0 hours of labor. A pushed-out or spread terminal may need a correct terminal repair rather than a complete sensor.

Accessible signal or return wiring repair: 10 to 400 dollars in parts, plus about 1.5 hours of labor. Cost rises when the open is inside a wrapped engine harness or shared splice.

Standalone intake-air-temperature sensor: 15 to 140 dollars in parts, plus about 0.5 hours of labor. Confirm the connector and response test first because many standalone sensors are easy to replace and easy to misdiagnose.

Integrated MAF, MAP or charge-pressure sensor: 60 to 550 dollars in parts, plus about 1.0 hours of labor. Replace the combined assembly only after proving its IAT element failed while its wiring remained intact.

PCM connector, software or module repair: 0 to 1600 dollars in parts, plus about 2.0 hours of labor. The rare final branch after the correct resistance and voltage relationship is proven at the controller.

Test the connector and circuit response before replacing an integrated sensor.

08:56Recap and related codes

Quick recap. P0113 means intake-air-temperature sensor 1 voltage stayed too high and usually translated to implausibly cold air; high input does not mean hot intake air. Compare cold-soak temperatures, preserve and inspect the connector, run the approved response test, trace signal and return circuits, and leave the PCM for last.

If your scan tool showed a related code alongside this one, check those too: P0111, P0112, P0101, P0098.

Codes are on screen and linked below.