Intake Air Temperature Sensor 2 Circuit Intermittent/Erratic Bank 1
The P0099 code indicates that the Engine Control Module (ECM) has detected an intermittent or erratic signal from the Intake Air Temperature (IAT) sensor 2 on bank 1. This sensor measures the temperature of the air entering the engine and is typically located in the intake air duct or manifold. An erratic signal can cause incorrect air-fuel mixture calculations, leading to performance issues. Common causes include a faulty sensor, damaged wiring or connectors, or corrosion in the circuit.
1. Most Common Causes
- Corroded, loose, or moisture-contaminated connector or terminals at the IAT2 sensor
- Wiring harness damage from chafing, intermittent short, or open circuit in the sensor circuit
- Internally failed IAT2 sensor producing an unstable output signal
- Poor sensor ground reference causing voltage fluctuations
- Electromagnetic interference in the harness near high-voltage components
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor engine performance or hesitation
- Decreased fuel economy
- Rough idle or stalling
3. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for other related codes.
Step 2: Visually inspect the IAT sensor 2 and its wiring for damage, corrosion, or loose connections.
Step 3: Test the sensor's resistance with a multimeter and compare to manufacturer specifications.
Step 4: Check the circuit for continuity and shorts to ground or power.
Step 5: If all else is fine, replace the IAT sensor 2 and clear the code.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is generally safe for short trips, but prolonged driving may cause poor performance and reduced fuel economy. It's best to diagnose and fix the issue promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150, including parts and labor. The sensor itself is usually inexpensive, but labor costs vary.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.