C051ALeft Rear Wheel Speed Sensor - Mechanical
- Generic OBD-II code · Chassis
- Can trigger limp mode
- Needs a drive cycle to confirm a fix
- How the car detects it
- C051A names a mechanical fault at the left rear sensor. Like its siblings it is listed but not documented by any manufacturer, so the actual setting rule is unknown. At the rear axle the encoder sits in different places: inside the hub bearing seal on many cars, as HELLA describes for multipole rings, or on the axle shaft or hub of rigid axles. Ford special service messages show the rear-specific risks: on Ford's F-53 motorhome chassis of 2020, rear axle tone rings bent during hub and rotor installation, and on 2021–2022 F-150 trucks with a three-quarter floating axle, metal particles on axle tone rings and sensors set rear sensor codes until the axle tubes were cleaned. Those Ford cases were stored as C0037 and C0036, not as C051A.
- What you may notice
- ABS lamp, sometimes only under load or on rough roads
- Rear wheel speed drops out or jitters in live data
- Likely causes
- LikelyMetal particles or rust on the rear encoder or sensor tip
- PossibleRear tone ring bent or cracked, often after hub or brake work
- PossibleLeft rear hub bearing worn, encoder seal damaged
- Repair
- Medium · Often possible to do yourself.Typical cost: €0 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.