CarScan
C0037Chassis

Left rear wheel speed sensor malfunction

Where to start

The rear left wheel. At the back the connector is usually easier to reach than at the front, and it suffers more from road salt. Same order: connector, wire, then the sensor.

Which wheel — and why ABS is often unreadable

The code names the wheel: rear left. Wheel speed sensors are the dirtiest parts on a car — they live next to the brake, in salt and dust — so the order is: the connector and the harness near the strut first, the sensor itself last. A wire rubbed through where it bends with the suspension is the usual find.

⚠️ And the part almost nobody says out loud: ABS codes are not readable through the standard socket on most cars. The ABS unit sits on its own bus, and a cheap adapter has no wire to it — see where the socket wires go. If your scanner shows this code at all, it reached the ABS unit; if it shows nothing about ABS, that is not a healthy car — it is an unreachable unit.

A code is not a diagnosis. It says which check failed, not which part to replace. Clearing it without repair only means the car will report it again in a few trips.

How to put together a report a mechanic will actually read

How the code is built

Letter — the systemChassis: brakes, ABS, suspension
Common or the maker's ownGeneric code: the same on every car
Number of the faultThe serial number inside that group — it does not say how serious the fault is

All codes in «Brakes, ABS and stability control»

How the app helps

CarScan reads this code from your car through an OBD-II adapter, shows whether it is active now or only stored, names the module that reported it, and puts it into a plain-text report for your mechanic.

See what the app does

Unfamiliar word? Open the glossary

What the letter and the four digits mean