Mercedes W205 C-Class Parking Sensor Replacement: Part Numbers, Diagnosis and Cost

The W205 C-Class is one of the most common cars we get parking sensor questions about, partly because there are a lot of them on the road and partly because the generation is now old enough that the original sensors are reaching the end of their service life.

Here is what applies specifically to this chassis.

Which cars this covers

W205 is the sedan, but the generation runs across four body styles and all of them use the same sensor family:

• W205 — sedan
• S205 — estate / wagon
• C205 — coupe
• A205 — cabriolet

Model years roughly 2015 through 2021 in the US, covering C300, C43 AMG, C63 AMG and C63 S, plus the C350e and C400 depending on market. The AMG cars use the same sensors as the C300 — the bumper is different, the sensor is not.

The part number

Rear positions and front inner positions take A0009055504. The two front outer corners take A0009055604, which is a different part despite the one-digit difference.

This matters more on the W205 than on some cars because the front bumper on AMG variants is busy — there is a lot going on down there and it is easy to assume all six front sensors are the same part when two of them are not.

If you are only doing the rear bumper, the whole thing is A0009055504 and you can stop worrying about it.

How many sensors does a W205 have?

It depends on the options, which is the honest answer and the reason we tell everyone to count rather than guess.

A car with the basic Parktronic package typically carries fewer sensors than one specified with Active Parking Assist, and the front bumper is where that difference shows up. Rear layouts are more consistent across the range.

Walk the bumper and count. It takes twenty seconds and it is the difference between ordering the right pack and ordering twice.

Finding the failed sensor on a W205

Ignition on, into reverse so the system arms, then rest a fingertip on each sensor in turn. Working sensors tick faintly and rapidly — you can feel it clearly through a fingertip and often hear it if the street is quiet. A dead one does nothing at all.

If you have a Mercedes-capable scanner it will name the position outright. A generic OBD-II reader will not — Parktronic sits on a bus those tools do not reach, which is why plenty of W205 owners plug in a cheap reader, get no codes at all, and conclude the problem must be elsewhere.

The two things that catch W205 owners out

Front bumper respray. These cars are low and the front bumper takes stone chips, so a lot of them have been refinished at some point. Ultrasonic sensors transmit through their own face and a heavy paint build damps the signal until the sensor stops answering. If your parking sensors died shortly after bodywork, that is very likely the cause and no wiring diagnosis will find it. Keep the coat thin — under roughly 120 microns total film.

One dead sensor kills everything. The module self-tests the whole array on start-up, and a sensor that fails to answer takes the entire system offline rather than offering partial coverage. So a red display and no parking aid at all usually means one $15 part, not a module failure. Owners routinely assume the worst here and get quoted accordingly.

Doing it once

The bumper has to come off to reach the sensors, and that is the bulk of the labour. If one sensor has failed at eight or nine years old, the rest in that bumper are the same age and have seen the same road salt and the same weather. Replacing the set while you are in there costs a fraction of what it costs to do the job twice.

We stock the A0009055504 in singles for a known-bad sensor, and in 4, 6 and 12-packs for doing a bumper or a whole car. Free shipping from California, one-year warranty, and we will confirm your part number against your VIN before you order.

Mercedes Parktronic PDC sensors — singles and multipacks →

Need the A0009055604 front outers for a W205? Message us with your VIN and we will sort the pair.