Code P0098: Intake Air Temperature Sensor 2 Circuit High
Meaning of Error Code P0098
The generic code P0098 is a Diagnostic Trouble Code (DTC) related to the powertrain, applicable to most OBD-II equipped vehicles. It indicates that the Powertrain Control Module (PCM) has detected an abnormally high voltage (above 5 volts) in the Intake Air Temperature (IAT) sensor #2 circuit.
The PCM sends a 5-volt reference voltage to the IAT sensor, a thermistor whose resistance varies with temperature. A low resistance (due to high temperature) generates a low signal voltage, and vice versa. Code P0098 is triggered when the PCM receives a signal voltage that is too high, indicating excessive resistance in the circuit.
Symptoms of Code P0098
This code is often asymptomatic, but you may observe:
- The Malfunction Indicator Lamp (MIL) illuminated on the dashboard.
- A slight drop in performance or an increase in fuel consumption.
- In rare cases, the vehicle may enter a reduced power mode (“limp mode”).
Possible Causes of Code P0098
Several failures can cause this code:
- Faulty IAT Sensor #2: Internal failure of the thermistor.
- Connection Issues: Oxidized, loose, or corroded sensor connector.
- Wiring Problems: Short to voltage in the signal circuit or an open ground circuit.
- Electrical Interference: Wiring routed too close to high-voltage components (alternator, spark plugs).
- Faulty PCM: A rare, but possible cause.
Diagnosis and Solutions for Repairing Code P0098
Here is a step-by-step diagnostic procedure:
- Diagnostic Tool Check: Connect an OBD2 scanner. Observe the live data for the IAT sensor #2. A constantly low reading (e.g., -40°C) or erratic reading indicates a problem.
- Sensor and Wiring Test:
- Disconnect the IAT sensor connector.
- Using a jumper wire, short the signal pin to the ground pin on the harness connector.
- The reading on the scanner should immediately reach its maximum value (e.g., > 140°C). If it does, the wiring is healthy and the sensor is most likely faulty. If not, the problem lies with the wiring or the PCM.
- Electrical Test: Use a digital multimeter (DVOM) to check for the presence of the 5-volt reference voltage and the integrity of the circuits (no short circuits, ground continuity).
- Visual Inspection: Carefully inspect the connector, wiring, and sensor for any signs of damage, corrosion, or burning.
Common Repairs: Replacing the faulty IAT sensor #2 or repairing the wiring/open circuit usually resolves the issue.
Related IAT Sensor Codes
P0095, P0096, P0097, P0099, P0110, P0111, P0112, P0113, P0114
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