What is the P0110 Code?
P0110 is a generic OBD-II powertrain-related error code. It indicates a malfunction in the Intake Air Temperature (IAT) sensor circuit, sensor 1. This code signifies that the Powertrain Control Module (PCM) has detected an abnormal voltage from the IAT sensor outside the normal operating range.
Role and Operation of the IAT Sensor
The Intake Air Temperature (IAT) sensor is a thermistor. Its electrical resistance changes according to the temperature of the air it measures. It is typically installed in the air intake duct or intake manifold.
The PCM sends a 5-volt reference voltage to the sensor. As the air temperature changes, the sensor’s resistance varies, altering the signal voltage returned to the PCM. The PCM interprets this voltage to calculate the air temperature. Cold air increases resistance and voltage, while warm air decreases resistance and voltage.
Symptoms of the P0110 Code
- Malfunction Indicator Lamp (MIL) illuminated on the dashboard.
- Incorrect air-fuel ratio.
- Reduced engine power.
- Increased fuel consumption.
- Irregular idling.
- In some cases, no noticeable symptoms may appear.
Possible Causes of the P0110 Code
- Faulty IAT Sensor: The sensor itself is not functioning.
- Electrical Circuit Issues: Short to ground or power, open circuit, damaged wiring.
- Connector Problems: Corroded, loose, or damaged terminals/connectors.
- Improper Sensor Installation: Sensor is dislodged and not in the airflow.
- PCM Issues: Internal failure of the control module (rare).
Diagnosis and Solutions for Fixing P0110
Preliminary Checks
- Visual Inspection: Check if the IAT sensor is properly installed and if the air ducts are loose or have holes.
- Connector Check: Inspect the sensor’s electrical connector for corrosion, damage, or loose wiring.
Testing with Diagnostic Tools
- Turn the key to ON (engine off) when the engine is cold.
- Use a diagnostic tool to compare the values of the IAT sensor and the Coolant Temperature Sensor (CTS). They should be very close (within a few degrees).
- If the IAT value shows an extreme temperature (e.g., -40°C or +300°C), it confirms an issue.
Electrical Testing of the Sensor
- Disconnect the IAT sensor connector.
- Set a multimeter to ohmmeter mode and measure the resistance between the two pins of the sensor.
- Compare the reading with the manufacturer’s specifications (available in repair manuals). Infinite resistance (open circuit) or zero resistance (short circuit) indicates a faulty sensor that needs replacement.
Advanced Circuit Diagnosis
If the reading is very high (around 300°C):
- Disconnect the sensor. If the reading changes to a very low value (around -50°C), replace the IAT sensor.
- If the reading does not change, use a multimeter to check for a short to ground in the signal wire. If continuity to ground is present, repair the wiring.
If the reading is very low (around -50°C):
- Disconnect the sensor and check for the presence of a 5V reference voltage and a good ground at the vehicle-side connector.
- If 5V and ground are present, short the two pins of the vehicle-side connector. If the diagnostic tool reading changes to a very high value, replace the sensor.
- If 5V is not present, check the circuit to the PCM for an open wire.
Related DTC Codes
P0095, P0096, P0097, P0098, P0099, P0111, P0112, P0113, P0114, P0127
Conclusion and Call to Action
The P0110 code is often resolved by replacing the IAT sensor, which is typically an inexpensive part. However, careful verification of the electrical circuit is essential to avoid unnecessary part replacements.
Don’t have a diagnostic tool or unsure about performing these steps? Leave the diagnosis to a professional mechanic. They can quickly identify and resolve the issue, ensuring your vehicle operates correctly.
