What is the P0113 Code?
The trouble code P0113 is a generic OBD-II (On-Board Diagnostics) powertrain-related code. It indicates that the Powertrain Control Module (PCM) has detected an abnormally high input voltage in the Intake Air Temperature (IAT) sensor circuit 1. Although it is a generic code, specific diagnostic procedures may vary depending on the vehicle’s manufacturer and model.
How the IAT Sensor Works
The PCM sends a 5-volt reference voltage to the IAT sensor. This sensor is a thermistor, meaning its electrical resistance changes with the temperature of the intake air.
- Cold Air: High resistance → High signal voltage
- Warm Air: Low resistance → Low signal voltage
The P0113 code is triggered when the PCM detects a signal voltage exceeding 4.5-5 volts (indicating an unrealistically low temperature, such as below -30°C).
Symptoms of the P0113 Code
This trouble code often presents few symptoms noticeable to the driver:
- Illumination of the Malfunction Indicator Lamp (MIL) or “Check Engine” light
- Slight decrease in performance or fuel economy
- In some cases, the vehicle may enter Limp Mode (reduced power mode)
Potential Causes of the P0113 Code
The following issues can cause this code:
- Internal failure of the IAT sensor (most common cause)
- Poor connection: Loose, corroded, or damaged IAT sensor connector
- Wiring problems: Short to power in the signal circuit or open in the ground circuit
- Electrical interference: IAT sensor harness placed too close to high-voltage components (spark plugs, alternator)
- PCM failure (rare, but possible)
Diagnosis and Repair
Here is a step-by-step diagnostic procedure to identify and resolve the cause of the P0113 code.
1. Verification with a Diagnostic Tool
Connect an OBD-II scan tool and observe the IAT temperature value in real-time.
- If the displayed value is plausible (e.g., 10°C on a cold day), the issue is likely intermittent. Check for loose wiring connections.
- If the displayed value is abnormally low (e.g., -40°C), proceed with the following tests.
2. Testing the Sensor and Wiring
Procedure A: With the ignition OFF, disconnect the IAT sensor connector. Connect a jumper wire between the signal pin and ground pin on the harness side connector. Turn the ignition ON (without starting the engine) and check the IAT reading on the scan tool.
- If the reading becomes very high (e.g., >120°C), the wiring is okay. Replace the IAT sensor.
- If the reading remains low, there is a problem with the wiring or the PCM.
Procedure B: Use a Digital Multimeter (DVOM) to measure the voltage between the signal wire and ground.
- It should read approximately 5 volts. If no voltage is present, check for an open circuit in the PCM’s 5V reference circuit.
- Check the continuity and for shorts in each wire (signal, ground, reference voltage) between the PCM connector and the IAT sensor connector.
3. Cleaning and Replacement
Visually inspect the connector and sensor for corrosion or damage. Clean the terminals if necessary. If the previous tests indicate a faulty sensor, replace it with an OEM quality part.
Related DTC Codes
Other codes related to the IAT sensor circuit: P0110, P0111, P0112, P0114
Summary and Call to Action
The P0113 code is often resolved by replacing the IAT sensor, which is a relatively accessible and low-cost component. However, accurate diagnosis using a scan tool and multimeter is essential to avoid unnecessary part replacement.
Unsure about performing these tasks? For your vehicle’s diagnosis and repair, consult a certified professional mechanic. They possess the expertise and equipment to efficiently resolve the issue and ensure your engine’s proper operation.
