P0791: Intermediate Shaft Speed Sensor A Circuit

Definition

The OBD2 code P0791 indicates a malfunction in the Intermediate Shaft Speed Sensor A circuit, which typically relates to issues with the sensor's performance or its electrical connections, affecting the transmission's ability to determine the speed of the intermediate shaft

Common causes

Faulty intermediate shaft speed sensor
Damaged wiring or connectors
Poor electrical connections
Faulty transmission control module (TCM)
Internal transmission issues
Incorrectly installed or misaligned sensor

Common misdiagnoses

Transmission issues
Faulty transmission control module (TCM)
Incorrectly diagnosed speed sensor problems
Wiring or connector issues
Engine control module (ECM) faults
Problems with the torque converter
Incorrectly diagnosed engine performance issues

Troubleshooting steps

1. Check for Additional Codes

Use an OBD-II scanner to check for any other trouble codes that may be present. This can provide more context and help identify related issues
2. Inspect the Intermediate Shaft Speed Sensor
3. Locate the Intermediate Shaft Speed Sensor and visually inspect it for any signs of damage, corrosion, or loose connections
4. Ensure that the sensor is securely mounted and that there are no obstructions
5. Check Wiring and Connectors
6. Inspect the wiring harness and connectors leading to the sensor for any signs of wear, fraying, or damage
7. Look for any loose or corroded connections that could affect the sensor's operation
8. Test the Sensor
9. Use a multimeter to test the resistance of the sensor according to the manufacturer's specifications. If the resistance is outside the specified range, the sensor may need to be replaced
10. If possible, check the sensor's output signal while the vehicle is running to ensure it is functioning correctly
11. Inspect the Transmission Fluid
12. Check the transmission fluid level and condition. Low or contaminated fluid can affect sensor performance and transmission operation
13. If the fluid is dirty or burnt, consider changing it and replacing the filter
14. Check the Transmission Control Module (TCM)
15. Inspect the TCM for any signs of damage or corrosion
16. If other components are functioning correctly, the TCM may need to be reprogrammed or replaced
17. Clear the Codes and Test Drive
18. After performing any repairs or replacements, clear the trouble codes using the OBD-II scanner
19. Take the vehicle for a test drive to see if the code reappears. Monitor the transmission performance during the drive
20. Consult Repair Manual or Professional Help
21. If the issue persists after following the above steps, consult the vehicle's repair manual for specific diagnostic procedures related to the P0791 code
22. Consider seeking help from a professional mechanic or technician who has experience with transmission issues. By following these troubleshooting steps, you can identify and resolve the underlying issue causing the P0791 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect the Intermediate Shaft Speed Sensor

3. Locate the Intermediate Shaft Speed Sensor and visually inspect it for any signs of damage, corrosion, or loose connections

4. Ensure that the sensor is securely mounted and that there are no obstructions

5. Check Wiring and Connectors

6. Inspect the wiring harness and connectors leading to the sensor for any signs of wear, fraying, or damage

7. Look for any loose or corroded connections that could affect the sensor's operation

8. Test the Sensor

9. Use a multimeter to test the resistance of the sensor according to the manufacturer's specifications. If the resistance is outside the specified range, the sensor may need to be replaced

10. If possible, check the sensor's output signal while the vehicle is running to ensure it is functioning correctly

11. Inspect the Transmission Fluid

12. Check the transmission fluid level and condition. Low or contaminated fluid can affect sensor performance and transmission operation

13. If the fluid is dirty or burnt, consider changing it and replacing the filter

14. Check the Transmission Control Module (TCM)

15. Inspect the TCM for any signs of damage or corrosion

16. If other components are functioning correctly, the TCM may need to be reprogrammed or replaced

17. Clear the Codes and Test Drive

18. After performing any repairs or replacements, clear the trouble codes using the OBD-II scanner

19. Take the vehicle for a test drive to see if the code reappears. Monitor the transmission performance during the drive

20. Consult Repair Manual or Professional Help

21. If the issue persists after following the above steps, consult the vehicle's repair manual for specific diagnostic procedures related to the P0791 code

22. Consider seeking help from a professional mechanic or technician who has experience with transmission issues. By following these troubleshooting steps, you can identify and resolve the underlying issue causing the P0791 code