A scan tool showing -40°F for intake air on a summer day is a clear sign of trouble. The engine computer knows that reading cannot be real, so it sets a fault. A P0113 code means the intake air temperature sensor signal climbed above its highest allowed voltage.
This is one of the most common sensor codes, and it often has a simple cause. This guide shows you how to find it.
P0113 Code Breakdown
Every OBD-II code follows the same five-character pattern set by the SAE J2012 standard. Each character narrows down which system has the fault. This table shows what each part of the code tells you.
| Character | Meaning | What It Tells You |
|---|---|---|
| P | Powertrain | The fault is in the engine or transmission systems. |
| 0 | Generic (SAE) code | The definition is the same on every OBD-II vehicle. |
| 1 | Fuel and air metering | The fault involves the sensors that measure air and fuel. |
| 13 | Specific fault | Intake Air Temperature Circuit High Input |
What the P0113 Code Means and How It Sets
The SAE J2012 standard defines the P0113 code as Intake Air Temperature Circuit High Input. “High input” refers to voltage, not temperature.
The intake air temperature (IAT) sensor is a thermistor whose resistance rises as air gets colder. The powertrain control module (PCM) sends it a 5-volt reference through a resistor. Cold air pushes the signal voltage up. When the circuit opens, the signal floats up to the full 5 volts, and the PCM reads the coldest value it can show, usually -40°F.
That makes an open circuit the most likely cause. An unplugged connector, a broken wire or a sensor that failed open all look the same to the PCM.
Symptoms of a High IAT Signal
A false cold reading makes the PCM think the air is dense. It may add extra fuel and advance timing. Common signs include:
- Check engine light on
- Rough idle, especially when warm
- Black smoke or a fuel smell from a slightly rich mixture
- Hard starting when the engine is hot
- Worse fuel economy
Many engines run almost normally because the PCM switches to a default temperature once it sets the code.
What Causes the P0113 Code?
Open circuits cause most high input faults. These are the usual suspects:
- Unplugged connector. This is the top cause, often after air filter or intake work.
- Broken signal or ground wire. Wires can break near the connector from vibration.
- Corroded pins. Heavy corrosion can open the circuit.
- Failed IAT sensor. The thermistor can crack and open inside.
- Failed MAF sensor. When the IAT sensor is built into the MAF sensor, the unit must be replaced.
- Signal wire shorted to voltage. This is less common but pushes the signal high too.
Testing the IAT Circuit for a High Signal
Gather a digital multimeter, a scan tool and the wiring diagram for your engine. Start with a visual check, since a loose connector fixes many cases.
Check the Connector First
Find the IAT sensor, which is often part of the mass air flow sensor or mounted in the air box or intake tube. Make sure the connector is fully seated and its lock has clicked. Look for bent pins, green corrosion and a broken locking tab.
Clear the code and watch the IAT reading with the key on. If it now shows a sensible temperature, the connector was the problem.
Use the Jumper Test
Unplug the sensor and connect a fused jumper wire between the two connector pins. With the key on, the scan tool should jump to a very hot reading, often near 300°F.
If it does, the wiring and PCM are good, and the sensor is open. If the reading stays at -40°F, the signal or ground wire is broken between the connector and the PCM. Check each wire for continuity with the battery disconnected.
Measure the Sensor
Measure resistance across the sensor’s two pins. An open sensor reads infinite resistance, often shown as “OL” on the meter. A healthy sensor typically reads about 2,000 to 3,500 ohms at 68°F, though your service manual has the exact chart.
How to Fix the P0113 Code
Each repair matches a test result. Fix the cause, clear the code and drive the vehicle through a full warm-up.
- Loose connector: Reseat it until the lock clicks.
- Corroded pins: Clean them with contact cleaner or replace the pigtail.
- Broken wire: Repair it with solder and heat shrink tubing.
- Open sensor: Replace the IAT sensor, or the MAF sensor if the IAT sensor is built in.
Repair Cost Guide
Costs depend on whether the IAT sensor stands alone or sits inside the MAF sensor. This table lists typical ranges.
| Repair | DIY Cost | Typical Shop Cost |
|---|---|---|
| Reseat or clean connector | $0 to $15 | $50 to $100 |
| Wiring repair | $10 to $30 | $100 to $300 |
| Standalone IAT sensor | $15 to $60 | $75 to $150 |
| MAF sensor with built-in IAT | $80 to $350 | $150 to $500 |
Why You Should Not Ignore the P0113 Code
The engine usually keeps running, but the default air temperature is a compromise. On hot days, the PCM may add more fuel than needed, which wastes gas and can foul spark plugs over time.
A stored code also keeps the check engine light on. That can hide a new, more serious fault that sets later, and your car will fail an OBD-II emissions test.
Related Codes
These codes often show up with this one or point to the same system:
| Code | Meaning |
|---|---|
| P0110 | Intake Air Temperature Circuit Malfunction |
| P0111 | Intake Air Temperature Circuit Range/Performance Problem |
| P0112 | Intake Air Temperature Circuit Low Input |
| P0114 | Intake Air Temperature Circuit Intermittent |
| P0115 | Engine Coolant Temperature Circuit Malfunction |
Bringing a High IAT Signal Back to Normal
A P0113 code means the PCM sees a voltage that reads as extremely cold air. An open circuit, often just a loose connector, causes most cases.
- Check that the connector is fully seated and locked.
- Use the jumper test to split wiring from sensor faults.
- Measure sensor resistance for an open element.
- Replace the sensor only after the wiring tests good.
Frequently Asked Questions
Why Does My IAT Sensor Read -40°F?
A reading of -40°F is the lowest value most scan tools display. It appears when the sensor circuit is open, so the PCM sees the full reference voltage. An unplugged connector, broken wire or failed sensor causes it. Real outside air almost never reaches that temperature.
Can a Cold Air Intake Cause a P0113 Code?
A cold air intake install often means moving the IAT sensor or extending its wires. A loose connector, a pin pushed out of the housing or a stretched wire can open the circuit. Recheck the connection and wire routing first if the code appeared after an intake upgrade.
Will the Check Engine Light Turn Off on Its Own?
The light can turn off after several drive cycles if the fault does not return. The code stays in memory for a while, though. Clearing it with a scan tool after the repair is faster and lets you confirm right away that the IAT reading looks normal again.
Is the IAT Sensor the Same as the MAF Sensor?
The two are different sensors, but many vehicles house them together. The MAF sensor measures airflow, while the IAT sensor measures air temperature. When they share one housing, a failed IAT element means replacing the whole MAF assembly, which costs more than a standalone IAT sensor.