C1124: Input shaft speed signal missing/faulted

Definition

The OBD2 code C1124 indicates that the input shaft speed signal is missing or faulty, which typically means the vehicle's transmission control module is not receiving a valid signal from the input shaft speed sensor, affecting transmission performance

Common causes

Faulty input shaft speed sensor
Damaged wiring or connectors
Poor electrical connections
Malfunctioning transmission control module (TCM)
Issues with the vehicle's powertrain control module (PCM)
Mechanical failure in the transmission
Software issues or glitches in the TCM/PCM
Low transmission fluid levels or contamination

Common misdiagnoses

Faulty speed sensor
Wiring issues or shorts
Transmission control module (TCM) failure
Engine control module (ECM) issues
Incorrectly installed or damaged transmission
Low transmission fluid levels
Faulty torque converter
Wheel speed sensor problems
ABS module issues
Calibration errors or software glitches

Troubleshooting steps

1. Check for Additional Codes

Use an OBD-II scanner to check for any other related trouble codes. This can provide more context and help identify if there are other issues present
2. Inspect Wiring and Connectors
3. Visually inspect the wiring and connectors related to the input shaft speed sensor. Look for signs of damage, corrosion, or loose connections
4. Ensure that the connectors are securely attached and that there are no broken wires
5. Test the Input Shaft Speed Sensor
6. Locate the input shaft speed sensor and test its resistance and voltage output according to the manufacturer's specifications
7. If the sensor is faulty, it may need to be replaced
8. Check the Transmission Fluid
9. Inspect the transmission fluid level and condition. Low or dirty fluid can affect sensor performance
10. If the fluid is low, top it off with the correct type of transmission fluid. If it is dirty, consider a transmission fluid change
11. Inspect the Transmission Control Module (TCM)
12. Check for any issues with the TCM, as it processes signals from the input shaft speed sensor
13. Ensure that the TCM is functioning properly and that there are no software issues
14. Look for Mechanical Issues
15. Inspect the transmission for any mechanical problems that could affect the input shaft speed, such as worn gears or clutches
16. If there are any signs of internal transmission failure, further diagnosis may be required
17. Perform a Visual Inspection of the Transmission
18. Check for any leaks or signs of damage to the transmission housing
19. Ensure that all components are properly secured and in good condition
20. Clear the Codes and Test Drive
21. After performing the necessary repairs or adjustments, clear the trouble codes using the OBD-II scanner
22. Take the vehicle for a test drive to see if the code reappears
23. Consult Technical Service Bulletins (TSBs)
24. Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to the C1124 code
25. Seek Professional Help
26. If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who specializes in transmission diagnostics. By following these troubleshooting steps, you can systematically identify and resolve the issue related to the C1124 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check for Additional Codes

2. Inspect Wiring and Connectors

3. Visually inspect the wiring and connectors related to the input shaft speed sensor. Look for signs of damage, corrosion, or loose connections

4. Ensure that the connectors are securely attached and that there are no broken wires

5. Test the Input Shaft Speed Sensor

6. Locate the input shaft speed sensor and test its resistance and voltage output according to the manufacturer's specifications

7. If the sensor is faulty, it may need to be replaced

8. Check the Transmission Fluid

9. Inspect the transmission fluid level and condition. Low or dirty fluid can affect sensor performance

10. If the fluid is low, top it off with the correct type of transmission fluid. If it is dirty, consider a transmission fluid change

11. Inspect the Transmission Control Module (TCM)

12. Check for any issues with the TCM, as it processes signals from the input shaft speed sensor

13. Ensure that the TCM is functioning properly and that there are no software issues

14. Look for Mechanical Issues

15. Inspect the transmission for any mechanical problems that could affect the input shaft speed, such as worn gears or clutches

16. If there are any signs of internal transmission failure, further diagnosis may be required

17. Perform a Visual Inspection of the Transmission

18. Check for any leaks or signs of damage to the transmission housing

19. Ensure that all components are properly secured and in good condition

20. Clear the Codes and Test Drive

21. After performing the necessary repairs or adjustments, clear the trouble codes using the OBD-II scanner

22. Take the vehicle for a test drive to see if the code reappears

23. Consult Technical Service Bulletins (TSBs)

24. Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to the C1124 code

25. Seek Professional Help

26. If the issue persists after performing the above steps, it may be necessary to consult a professional mechanic or technician who specializes in transmission diagnostics. By following these troubleshooting steps, you can systematically identify and resolve the issue related to the C1124 code