Sensors and circuits
P0113Intake air temperature sensor circuit high input
Intake Air Temperature Sensor 1 Circuit High Bank 1
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Generic OBD-II code
Intake Air Temperature (IAT) Sensor
What this part does
Measures the temperature of incoming air so the control module can adjust fuel and timing for air density.
What the computer is measuring
Air density changes with temperature. Cold air is denser, so a given volume of it contains more oxygen and needs more fuel to burn correctly. The intake air temperature sensor tells the computer how warm the air entering the engine is, so it can correct the fuelling and the ignition timing for that.
The sensor itself is a thermistor: a resistor whose resistance changes with temperature. The computer feeds it a reference voltage through a fixed resistor and reads the voltage that comes back. Hot air means low resistance and a low voltage. Cold air means high resistance and a high voltage.
That arrangement is what makes P0113 a wiring code more often than a sensor code. High input means the returned voltage is at or near the top of its range, which is exactly what an open circuit produces, because with nothing connected the voltage divider has nothing pulling it down. A disconnected plug, a broken wire and a sensor that has failed open all look identical to the computer.
The practical consequence runs the opposite way from what most people expect. High input means the computer is being told the incoming air is extremely cold, so it adds fuel to suit an air density that is not actually there. On a warm engine that shows up as a slightly rich, rough running condition rather than a starting problem. Many computers recognise an implausible reading and substitute a default instead, in which case the light is the only symptom you get.
Check the connector first. On this code it is the answer far more often than the sensor is.
What you will notice
- Steady check engine light.
- Rough running or hesitation once the engine is fully warm, because the computer is fuelling for air far colder than it really is.
- Occasionally a fuel smell or a puff of black smoke under load.
- Slightly worse fuel economy.
- Sometimes no drivability symptom at all, if the computer has fallen back to a default value.
Likely causes, most common first
Ordered by how often each one actually turns out to be the problem, not alphabetically and not by part price.
A disconnected or corroded sensor connector
The most common cause. An open circuit is exactly what a disconnected plug looks like, and this sensor is frequently unplugged during other work and not refitted.
A broken or chafed signal wire
Second most common. The wire runs across a vibrating engine and eventually breaks, usually where it is bent or clipped.
A failed sensor
The sensor is a thermistor, and it can fail open. Less common than the wiring, so test before replacing.
A poor or corroded ground connection
A bad ground on the sensor return makes a good sensor read as an open circuit.
Contamination on a combined mass air flow and intake air temperature sensor
On many engines the two are one part. Oil from an over oiled air filter coats the element and skews the reading.
What to check, in order
Find the sensor and check that it is plugged in, with clean and undamaged pins.
A disconnected or corroded plug is the whole answer surprisingly often, and it costs nothing to check.
Read the intake air temperature value with the engine cold, and compare it against the coolant temperature.
On an engine that has sat overnight, those two readings should be close to each other and close to ambient. A wildly low intake air reading, or a default extreme value, confirms the circuit fault.
Bridge the two sensor pins at the connector with the ignition on and watch the reading.
If the reading jumps to the opposite extreme, the wiring and the computer are fine and the sensor is the fault. If nothing changes, the fault is in the harness or the computer.
Check continuity on the signal and ground wires back toward the computer.
An open circuit found here is the fault, and no sensor needs replacing.
Where this one turns up most
- Vehicles that have recently had intake or air filter work, where the plug was left off.
- Engines with a combined mass air flow and temperature sensor and an oiled aftermarket filter.
Codes that often show up alongside it
What a DriveDecode adapter can read
A DriveDecode adapter reads engine and emissions systems: the powertrain and emissions codes the OBD-II standard requires on every US vehicle it covers. It does not read ABS, airbag (SRS), TPMS or transmission-specific manufacturer codes. Those need make-specific decoding that generic OBD-II hardware cannot do.
Reading P0113 on your own car
DriveDecode pulls P0113 straight off the vehicle along with the freeze frame the computer stored when it set: the coolant temperature, engine load and speed at that exact moment. That context is what separates a fault that happens on a cold start from one that happens under load, and it is the first thing the list above asks you to narrow down.
Last reviewed 2026-09-05. Definition sourced from the published standard.