DTC P0098 – Intake Air Temperature Sensor 2 Circuit High

Meaning

P0098 indicates that the Intake Air Temperature (IAT) Sensor 2 is reporting a voltage that is higher than the expected range, meaning the ECM sees the temperature as extremely low (because high voltage = low temperature in NTC thermistor sensors).

This typically applies to vehicles that have multiple IAT sensors (e.g., turbocharged engines).

🎉Common Symptoms:

Check Engine Light ON

Poor throttle response

Hard starting (cold)

Reduced fuel efficiency

High fuel consumption

Turbo boost performance issues (in forced-induction engines)

🎉Common Causes:

1. Open circuit in the IAT2 sensor wiring

2. Unplugged / loose connector

3. Damaged sensor

4. Corroded or dirty connector pins

5. Broken wires near the sensor

6. Short-to-voltage (5V reference touching signal wire)

7. Faulty PCM/ECM (rare)

🎉Quick Checks (Fast Diagnosis)

1. Visual Inspection

Locate IAT Sensor 2 (often integrated in charge air temp sensor, MAP sensor, or MAF sensor depending on model).

Check for:

Loose connector

Sensor contamination
(oil/soot)

Damaged wiring harness

Corrosion on pins

2. Clear Code & Perform Wiggle Test

Start engine and wiggle the harness → If the code returns, wiring fault is likely.

Detailed Diagnostic Steps

Step 1: Check Sensor Wiring

Expected voltage key ON:

5V reference on the reference wire

Ground on ground wire

Signal wire typically ~2–3V at ambient temp

If signal wire shows ≈5V, the circuit is open → Replace sensor or repair wiring.

Step 2: Test IAT2 Sensor Resistance

IAT sensors are NTC thermistors:

Temperature Expected Resistance

0°C 10–12 kΩ
20°C 2–3 kΩ
40°C 1 kΩ
80°C 300–400 Ω

If resistance is infinite (open) → Sensor is faulty.

Step 3: Check for Short-to-Voltage

Use multimeter:

Disconnect the sensor

Back-probe signal wire → If you see 5V, you have a short to reference voltage

Trace wiring for rubbing or melted insulation

Step 4: Check Live Data

With scanner, monitor IAT2 temp:

If it shows –40°C → The ECM sees OPEN circuit → Replace sensor or repair wiring.

🎉Most Common Fixes

✅ Clean and reseat the connector
✅ Repair broken wire or pin
✅ Replace faulty IAT2 sensor
✅ Replace MAF/MAP sensor (if IAT2 is integrated)
✅ Fix short-to-voltage in harness
✅ Rare: PCM/ECM reflash or replacement

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