What is the P0113 Code?
The P0113 trouble code is a generic OBD-II (On-Board Diagnostics) code related to the powertrain. It indicates that the Powertrain Control Module (PCM) has detected an abnormally high input voltage in the Intake Air Temperature (IAT) Sensor Circuit No. 1. Although generic, specific diagnostic procedures may vary by vehicle make and model.
IAT Sensor Operation
The PCM sends a 5-volt reference voltage to the IAT sensor. This sensor is a thermistor: its electrical resistance changes based on the temperature of the intake air.
- Cold Air: High resistance → High signal voltage.
- Hot Air: Low resistance → Low signal voltage.
The P0113 code is triggered when the PCM measures a signal voltage higher than 4.5-5 volts, which corresponds to an unrealistic and extremely low temperature reading (e.g., below -30°C).
Symptoms of the P0113 Code
This trouble code is often accompanied by mild symptoms noticeable to the driver:
- Illumination of the Malfunction Indicator Lamp (MIL) or “Check Engine” light.
- Slight decrease in performance or fuel efficiency.
- In some cases, the vehicle may enter a reduced power mode (“limp mode”).
Possible Causes of the P0113 Code
Several malfunctions can cause this code:
- Internal IAT sensor failure (most common cause).
- Connection issue: Loose, corroded, or damaged IAT sensor connector.
- Wiring problem: Short to voltage in the signal circuit or open ground circuit.
- Electrical interference: IAT sensor harness routed too close to high-voltage components (spark plugs, alternator).
- PCM failure (rare but possible).
Diagnosis and Solutions
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 real-time IAT temperature value.
- If the reading is plausible (e.g., 10°C on a cold day), the problem is likely intermittent. Check the wiring for loose connections.
- If the reading is abnormally low (e.g., -40°C), proceed to the following tests.
2. Sensor and Wiring Test
Step A: With the ignition off, disconnect the IAT sensor connector. Install a jumper wire between the signal pin and the ground pin of the harness connector. Turn the ignition on (without starting the engine) and observe the IAT reading on the scan tool.
- If the reading is now very high (e.g., > 120°C), the wiring is correct. Replace the IAT sensor.
- If the reading remains low, there is a problem with the wiring or the PCM.
Step B: Use a digital multimeter (DVOM) to measure the voltage between the signal wire and ground.
- You should measure approximately 5 volts. If voltage is absent, check the PCM’s 5V reference circuit for a break.
- Check the continuity and absence of short circuits for each wire (signal, ground, reference) 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 previous tests indicate a faulty sensor, replace it with a quality OEM part.
Related DTC Codes
Other codes related to the IAT sensor circuit include: P0110, P0111, P0112, P0114.
Conclusion and Call to Action
The P0113 code is often resolved by replacing the IAT sensor, a relatively accessible and inexpensive component. However, accurate diagnosis with a scan tool and multimeter is essential to avoid unnecessary part replacements.
Not comfortable performing these procedures? Entrust the diagnosis and repair of your vehicle to a certified professional mechanic. They have the expertise and equipment needed to resolve the issue effectively and ensure your engine’s proper operation.