P1635: Tire / Axle Ratio Out of Acceptable Range

Definition

The OBD2 code P1635 indicates that the tire or axle ratio is outside the acceptable range, which can affect the vehicle's speedometer accuracy and overall performance

Common causes

Incorrect tire size
Incorrect axle ratio
Faulty wheel speed sensors
Malfunctioning ABS module
Faulty engine control module (ECM)
Wiring issues or poor connections
Calibration errors after tire or axle changes

Common misdiagnoses

Wheel speed sensor issues
ABS module failure
Transmission problems
Incorrect tire size
Differential issues
PCM (Powertrain Control Module) faults
Speedometer calibration errors
Wiring or connector problems

Troubleshooting steps

1. Check Tire Sizes
2. Ensure that all tires are the correct size as specified by the manufacturer. Mismatched tire sizes can lead to incorrect readings and trigger the P1635 code
3. Inspect the Axle Ratio
4. Verify that the axle ratio is correct for your vehicle. If the axle has been changed or modified, it may not match the vehicle's specifications
5. Examine the Speed Sensors
6. Check the vehicle speed sensor (VSS) and any associated wiring for damage or corrosion. A faulty speed sensor can send incorrect data to the engine control module (ECM)
7. Check for Software Updates
8. Sometimes, the vehicle's ECM may require a software update. Check with the manufacturer or a qualified technician to see if there are any updates available
9. Inspect Wiring and Connectors
10. Look for damaged wiring or loose connections related to the speed sensor and the ECM. Repair or replace any damaged components
11. Clear the Code
12. After performing any repairs or adjustments, clear the code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns
13. Perform a Visual Inspection
14. Conduct a thorough visual inspection of the drivetrain components, including the differential and transmission, for any signs of wear or damage
15. Check for Other Codes
16. Look for any other related trouble codes that may provide additional context for the issue. Addressing other codes may resolve the P1635 code as well
17. Consult Technical Service Bulletins (TSBs)
18. Check for any TSBs related to your vehicle model that may address known issues with the tire or axle ratio
19. Professional Diagnosis
20. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership for a more in-depth diagnosis. By following these troubleshooting steps, you should be able to identify and resolve the issue causing the P1635 code

Definition

Common causes

Common misdiagnoses

Troubleshooting steps

1. Check Tire Sizes

2. Ensure that all tires are the correct size as specified by the manufacturer. Mismatched tire sizes can lead to incorrect readings and trigger the P1635 code

3. Inspect the Axle Ratio

4. Verify that the axle ratio is correct for your vehicle. If the axle has been changed or modified, it may not match the vehicle's specifications

5. Examine the Speed Sensors

6. Check the vehicle speed sensor (VSS) and any associated wiring for damage or corrosion. A faulty speed sensor can send incorrect data to the engine control module (ECM)

7. Check for Software Updates

8. Sometimes, the vehicle's ECM may require a software update. Check with the manufacturer or a qualified technician to see if there are any updates available

9. Inspect Wiring and Connectors

10. Look for damaged wiring or loose connections related to the speed sensor and the ECM. Repair or replace any damaged components

11. Clear the Code

12. After performing any repairs or adjustments, clear the code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns

13. Perform a Visual Inspection

14. Conduct a thorough visual inspection of the drivetrain components, including the differential and transmission, for any signs of wear or damage

15. Check for Other Codes

16. Look for any other related trouble codes that may provide additional context for the issue. Addressing other codes may resolve the P1635 code as well

17. Consult Technical Service Bulletins (TSBs)

18. Check for any TSBs related to your vehicle model that may address known issues with the tire or axle ratio

19. Professional Diagnosis

20. If the issue persists after performing the above steps, consider seeking help from a professional mechanic or dealership for a more in-depth diagnosis. By following these troubleshooting steps, you should be able to identify and resolve the issue causing the P1635 code