P0666: Intake Air Temperature Sensor 1 Circuit Short to Battery

Definition

The OBD2 code P0666 indicates that there is a short circuit in the Intake Air Temperature Sensor 1 circuit, causing it to be connected directly to the battery voltage, which can lead to incorrect readings and affect engine performance

Common causes

Shorted wiring or connectors
Faulty intake air temperature sensor
Corroded or damaged connectors
Poor ground connection
Open circuit in the wiring
Malfunctioning engine control module (ECM)

Common misdiagnoses

Faulty intake air temperature sensor
Wiring issues or shorts in the harness
Engine control module (ECM) failure
Mass air flow sensor problems
Vacuum leaks
Other sensor malfunctions (e.g., coolant temperature sensor)
Fuel system issues
Throttle position sensor problems

Troubleshooting steps

1. Visual Inspection
2. Check the wiring and connectors associated with the IAT sensor for any signs of damage, corrosion, or loose connections
3. Look for any frayed wires or exposed conductors that could be causing a short circuit
4. Check the IAT Sensor
5. Test the IAT sensor itself using a multimeter. Measure the resistance of the sensor at different temperatures to ensure it is functioning within specifications
6. If the sensor is faulty, replace it
7. Inspect the Circuit
8. Use a wiring diagram to trace the IAT sensor circuit back to the Engine Control Module (ECM). Check for continuity and shorts in the wiring
9. Look for any pinched or damaged wires that could be causing a short to battery
10. Check for Short to Battery
11. With the vehicle off, use a multimeter to check for continuity between the IAT sensor signal wire and the battery positive terminal. If there is continuity, there is a short in the circuit
12. Inspect the circuit for any points where the wire may be touching the chassis or other components that could cause a short
13. Inspect the ECM
14. If the wiring and sensor are in good condition, the issue may lie with the Engine Control Module (ECM). Check for any signs of damage or corrosion on the ECM connectors
15. If necessary, perform a reprogramming or replacement of the ECM
16. Clear the Code and Test Drive
17. After addressing any issues found, clear the trouble code using an OBD-II scanner
18. Take the vehicle for a test drive to see if the code returns. Monitor the IAT sensor readings to ensure they are within normal operating ranges
19. Consult Technical Service Bulletins (TSBs)
20. Check for any manufacturer-specific TSBs related to the P0666 code for your vehicle make and model. There may be known issues or recalls that could provide additional guidance
21. Seek Professional Help
22. If you are unable to resolve the issue after these steps, consider seeking help from a professional mechanic or automotive technician who has experience with OBD-II diagnostics. By following these steps, you should be able to identify and resolve the issue causing the P0666 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Visual Inspection

2. Check the wiring and connectors associated with the IAT sensor for any signs of damage, corrosion, or loose connections

3. Look for any frayed wires or exposed conductors that could be causing a short circuit

4. Check the IAT Sensor

5. Test the IAT sensor itself using a multimeter. Measure the resistance of the sensor at different temperatures to ensure it is functioning within specifications

6. If the sensor is faulty, replace it

7. Inspect the Circuit

8. Use a wiring diagram to trace the IAT sensor circuit back to the Engine Control Module (ECM). Check for continuity and shorts in the wiring

9. Look for any pinched or damaged wires that could be causing a short to battery

10. Check for Short to Battery

11. With the vehicle off, use a multimeter to check for continuity between the IAT sensor signal wire and the battery positive terminal. If there is continuity, there is a short in the circuit

12. Inspect the circuit for any points where the wire may be touching the chassis or other components that could cause a short

13. Inspect the ECM

14. If the wiring and sensor are in good condition, the issue may lie with the Engine Control Module (ECM). Check for any signs of damage or corrosion on the ECM connectors

15. If necessary, perform a reprogramming or replacement of the ECM

16. Clear the Code and Test Drive

17. After addressing any issues found, clear the trouble code using an OBD-II scanner

18. Take the vehicle for a test drive to see if the code returns. Monitor the IAT sensor readings to ensure they are within normal operating ranges

19. Consult Technical Service Bulletins (TSBs)

20. Check for any manufacturer-specific TSBs related to the P0666 code for your vehicle make and model. There may be known issues or recalls that could provide additional guidance

21. Seek Professional Help

22. If you are unable to resolve the issue after these steps, consider seeking help from a professional mechanic or automotive technician who has experience with OBD-II diagnostics. By following these steps, you should be able to identify and resolve the issue causing the P0666 code