Tire/Axle Ratio Out of Acceptable Range
Findings, check these first
- Aftermarket axle gears installed without PCM update
- Oversize tires changing the effective ratio
- Wrong tire size programmed after a swap
- Failing vehicle speed input confusing the ratio check
- PCM calibration mismatch
Standard procedure
- Confirm actual tire size and axle ratio against the door sticker
- Check what ratio and tire revolutions are programmed in the PCM
- Reprogram the PCM for the installed gears and tires
- Verify the speed signal reads correctly on a road test
- Return to stock sizing if programming cannot accept the change
Code lookup
Type a code above, or start from a symptom or a common code.
Press / to jump to the box. Ford-enhanced powertrain, body, chassis and network codes. Generic P0xxx codes live on OBD Codes List.
Sources and review
Review: checked against the recorded source material.
- OBDII.pro: P1635 Ford definition
live reference page (obdii.pro)
Supports: Ford-family meaning for P1635: Tire / Axle Ratio Out of Acceptable Range
Fetched directly. obdii.pro is a publisher independent of the engine-codes family.
- P1635 FORD Code: Meaning, Causes, and Symptoms | OBD2 Codes
live reference page (obd2-codes.co)
Supports: Ford meaning for P1635: Tire / Axle Ratio Out of Acceptable Range
Fetched directly. obd2-codes.co phrasing matches the engine-codes family, so it counts as one publisher.
Last updated 2026-09-04.
Report a correction for P1635. Include your vehicle, the issue and a source if you have one.