Intake Air Temperature Circuit Malfunction Bank 1
The PCM detected an out-of-range voltage signal from the Intake Air Temperature (IAT) sensor. This thermistor measures incoming air temperature to optimize fuel mixture and timing, and when its signal falls outside normal parameters, the code sets. You may experience poor drivability or just a check engine light.
What You Might Notice
- Check engine light (MIL) illumination
- Poor fuel economy
- Rough idle or hesitation during acceleration
- Hard starting or cold start issues
- Lean or rich running condition
Most Common Causes
- 1
Faulty IAT Sensor
The IAT sensor itself has failed or drifted out of calibration, causing it to send incorrect voltage signals to the PCM regardless of actual air temperature.
- 2
Open or Shorted IAT Signal Circuit
The wiring between the IAT sensor and PCM is broken, shorted to ground, or shorted to voltage, preventing proper signal transmission.
- 3
Poor Electrical Connection at IAT
Corroded, loose, or backed-out terminals at the IAT sensor connector create intermittent or no electrical contact.
- 4
Open Ground Circuit to IAT
A broken or corroded ground wire connection prevents the sensor from completing its circuit, causing abnormal voltage readings.
How to Diagnose It
- 1
Check Faulty IAT Sensor — The IAT sensor itself has failed or drifted out of calibration, causing it to send incorrect voltage signals to the PCM regardless of actual air temperature.
- 2
Check Open or Shorted IAT Signal Circuit — The wiring between the IAT sensor and PCM is broken, shorted to ground, or shorted to voltage, preventing proper signal transmission.
- 3
Check Poor Electrical Connection at IAT — Corroded, loose, or backed-out terminals at the IAT sensor connector create intermittent or no electrical contact.
- 4
Check Open Ground Circuit to IAT — A broken or corroded ground wire connection prevents the sensor from completing its circuit, causing abnormal voltage readings.
How to Fix It
- 1
Replace IAT Sensor
Remove the faulty IAT sensor from the intake manifold or air intake tube and install a new OEM or quality aftermarket sensor. Ensure proper seating and torque specifications are met.
- 2
Inspect and Repair IAT Wiring
Check the IAT sensor harness and signal wire for cuts, corrosion, or damage. Repair or replace damaged sections of wiring, ensuring all connections are secure and properly routed away from heat sources.
- 3
Clean or Reconnect IAT Connector
Disconnect the IAT sensor connector and inspect for corrosion or debris. Clean contacts with electrical contact cleaner, reseat any backed-out terminals, and reconnect firmly until you hear a click.
- 4
Verify Ground Circuit Continuity
Use a multimeter to test continuity from the IAT sensor ground terminal to the engine block or PCM ground. Repair or replace any broken ground straps or corroded ground connections.
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