i have acquired a very low mileage 1997 S500coupe outfitted with the parktronic system. and i am experiencing strange behavior from it. especially from the front bumper sensors. never from the rear sensors. most of the time, when coming to a stop at a light, the dash sensors illuminate, but seeing nothing nearby, do nothing. but occassionally, with nothing nearby, the front sensors will fully illuminate as if there is a hazard close to being impacted and the audible will sound. i can go from an intersection with nothing close where this will occur. then to another one where i have a car next to me and yet no similar warnings will occur. why is this do you think? all ears.

Albert, a defective sensor can cause the problem you describe. Although the electrical connectors to all the sensors are weathertight, sometimes moisture can cause problems. MB dealers can check for trouble codes and determine which sensor is causing the problem if that's the case. The odds are that's the problem. Another possibility is minor bumper damage. I've seen many cases of sensors being slightly knocked out of their mounts by parking lot mis-haps. You have to look closely to see this. On the lighter side, I once saw a 140 that had it's bumper painted right over the sensors by a body shop that didn't know any better, but that was an easy one to diagnose!!! Good luck

REALLY?

could that explain the situation where at one intersection, nothing beside me the sensors alarm. and then a half mile down the road at an intersection where i am surrounded by traffic the sensors remain silent?

that doesn't make any sense to me.

personally, i wonder if the sensors are sensitive to microwaves or some other level of rfi/emi.

because these sensors seem to go weird in only certain locations - and always in those locations. yet never seem to go haywire elsewhere.

bumper has never been touched by another vehicle. sensors are in the same condition day in day out[i.e., same sensors in the same condition from the intersection where they indicate imminent impact to the intersection where they are closer to obstacles and sound no alarm].

my ears are still listening

This also happens to me. I think that it is the wires embedded in the road surface at intersections controlled by traffic lights that set it off. I find the Parktronic feature more of a nuisance than a help. I usually turn it off first thing. Its programmed to come on each time the car is started.

that's a very good answer. i shall try to validate it.

i also find myself turning it off. it is too bad that the default is on. i would rather the default be off so that i could turn it on when wanted.

i wonder if that could be arranged?

In the owner's manual under parktronic it should list a bunch of
factors that can cause the system to sporaticly freak.
These include weather like snow or rain, dirt or grime on sensors,
wax on sensors, RF or other things being transmitted from near by vehicles (radar jammers / radio equipment), cell towers, radio/tv towers, loud noises, underground wiring, metal plates or
man hole covers, excessive road heat or exhaust heat from cars,
ect...ect...ect.....just about anything that can mess up ultra-sonic
signals from the parktronic sensors.
It couldn't hurt to have the system checked for a faulty sensor
code however.
Best of luck.
DR.D

thnx, i have come to that conclusion that rf is the problem.

and that being the case, d-b was silly not to have made the default off, rather than on.

so dr d, is there i way that i can redo that switch? in other words, ordinarily the parktronic system will be OFF. and if i want it on, i can toggle the switch and turn it ON.

all ears.

Unfortuately not that I am aware of. The control module has no programming options and as a saftey feature reactivates with each key cycle. I suppose this is in case a driver switches the system off for some reason. A day later, they might have forgotten that the system was off. Back up assuming there will be a beep and whack-o. $1800 bumper smacker or worse.
Remember saftey saftey saftey.....that's the MB way.
I have never found a way to make the system default off.
Sorry.
DR.D

Very informative replies! Still, it wouldn't hurt to check codes.