Hello all,

For my (pre-facelift) W221 S350, I sometimes get this error message whilst driving at relatively low speeds (let's say between 10km/h and 60km/h) with the usual beep and message flash :

Distronic plus inoperative, consult owner's manual
Parktronic inoperative, consult owner's manual

Any idea what's causing this?

(By the way, both Distronic and Parktronic operate just fine)

Bad sensor(s)?

Try the small battery of the radar.. Otherwise re-calibration might help.

I have read it could be the auxiliairy battery in the rear is partially depleted,because of driving too little distance with too many electrical consumers on.

Not sure, had it twice and I suspect its interference from other cars..

I've seen this error message a couple of times. When I read fault codes with Star Diagnosis, it shows events of interference causing the system to switch off. I guess it could be RF interference on the bumper radar frequency or just reflections of the radar pulses that appear confusing for the control unit at times.

ON pre-face lift 221 cars, the parktronic and distronic close promiximity sensors are located inside the bumper. Shadow memory using DAS will show any interference errors which you can use to pinpoint a problem. I would lead more to a faulty sensor. Event memory will show any connection issues with the sensors. Either way, you will need access to a STAR system to diagnose properly.

There is no recalibration procedure for the close proximity sensors used for PTS and close proxmity distronic. Long range distronic sensor (center of grill) is the only sensor that requires calibration which is not used for parktronic at all.

on my 07 I would say once every other week while at a stop light would hear the long beep with the error message but would go away within 2 seconds. first few times brought it to the dealers attention but with no answer, but so far still works ok

Same here, but suprising no one has found a solution for it.

I've gotten the same warning once since buying my Bluetec but it was during a really sloppy snowstorm that featured lots of slush on the road.I assume that one of more of the system's sensors were obscured by the slop,thus causing the warning.Never got the warning again.

First of all, glad to see one of the real experts on-board since awhile (I figured a one year gap between posts).

In my case I did not see any connection issues in the event memory. I did not even try to figure out interference issues from the shadow memory. I've got the star kit (actually two, PartD and SDconnect) but most likely I would need instructions for this.

For early W221 cars there is a software update too for the bumper radar units. Mine have not been updated, according to one technical bulletin this could reduce the number of events when Parktronic Plus gets disabled?

listerone has a fresh car and even a bit different Distronic Plus implementation (if I remember right, it would come with ultrasound based sensors plus two short range radars plus the main radar while older cars have no ultrasound sensors but four short range radars behind the bumper). The radars tolerate surprisingly much snow but I have also seen once or twice the system switching off from a lot of slush covering the grill and the front bumper. This is quite reasonable unlike perhaps the other scenario where the system switches off.

I get this long beep with error message every now and then. Maybe once a week. Everything still works perfectly. Did anyone find out what might cause this?

Ok guys I figured it out. I noticed this happening with my pre-lift S65, more recently then ever. Its always at low speeds when your parktronic activates, generally at a red light, stop and go traffic etc. Start looking at the other cars around you, nine times out of ten there's a newer generation ford product lingering in the general vicinity. Its normally a higher end fusion, Taurus, Edge, Escape or their chrome plated Lincoln variants. I'm not sure what type of radar ford used to knockoff the Lexus LS460's self parking system (7 years later), or the BMW 7 series "kick under the rear bumper to open the trunk" feature but it always throws the error codes on my car and its so annoying. I'm wondering if Mercedes has a software update to cancel out the errors. What's bizarre is the Lexus LS never sends out any problems and I'm behind my mothers 7 series all the time and never have any issues with either of them. Has anyone had luck or heard of a software update on this matter?

There is a technical bulletin about the SW update that fixes certain Distronic short range radar issues. Depends on your build date if this fix could apply to your car.

Thank you so much I will definitely ask next time I'm in for service. Thank you for the information.

I notice it happens to me when I stop in back of a car with backup sensors. I wonder if it is RF interference from other cars

You have 2 or 3 batteries depending on the MY.

https://www.benzworld.org/forums/w22...s-550-a-2.html