P0098 - Intake Air Temperature Sensor 2 Circuit High
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System
Powertrain (Engine & Gearbox)
Related Fault Codes
Technical Description
P0098 is set when the Engine Control Module (ECM) detects a high voltage signal from the Intake Air Temperature (IAT) sensor 2. On forced induction engines, IAT 2 is typically located after the intercooler to monitor the efficiency of the cooling and the temperature of the charge air. Since these sensors are Negative Temperature Coefficient (NTC) thermistors, a high voltage usually signifies an open circuit or high resistance. The ECM uses this data to calculate air density and adjust fuel injection, ignition timing, and boost levels. This code often triggers a 'Limp Home' mode to protect the engine from pre-detonation (knocking).
Possible Causes
Faulty IAT sensor 2 (internal open circuit)
Wiring harness open circuit or connector corrosion
Poor ground connection at the sensor
Faulty ECM software or internal ECM failure
Symptoms
Recommended Solution
- Visual inspection: Check the IAT 2 sensor connector for corrosion or bent pins. Inspect the wiring loom for chafing or breaks.
- Voltage test: Disconnect the sensor. With ignition ON, check for a 5V reference signal and a stable ground connection.
- Resistance test: Measure the resistance across the sensor pins. Compare with factory specs (e.g., 2000-3000 Ohms at 20°C). If the reading is infinite (O.L), replace the sensor.
- Live data Analysis: Use a scan tool to monitor IAT 2 readings. If it reads -40°F/C, it confirms an open circuit/high voltage.
- Action: Replace the IAT 2 sensor or repair the wiring as necessary.
Mechanic's Tip
Before replacing expensive components, always double-check wiring and connections. 80% of all sensor faults are actually due to corroded contacts or broken wires.
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