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Discussion Starter #1 (Edited)
The left front Parktronic sensor keeps giving false positive alarms. Instantly up to max, then quickly back down to zero. Sometimes this occurs three or even 5 times in a row, by which time I probably have turned Parktronic off, but it re-enables on the next startup cycle. It is intermittent, and I have found no pattern - stationary/moving, uphill, downhill, turning/straight, sunlight/shadow, day/night, it can happen at any time. The front left still works normally for proximity sensing, all three other corners work normally.

Last fall one sensor was replaced, my dealer said it had shorted out and recorded an error code. The sensor was installed and painted to match.

During the start of the Winter the same thing happened, the dealer found no code but did clean out salt encrusted around the sensor.

This spring after winter storage the same problems again, so I had it looked at during my annual state inspection. No codes again but the bracket was broken (no exterior damage). They replaced the bracket.

The problem reoccurred again and it went back in to the dealer. Their report says they drove the vehicle and observed the problem, then replaced the other two front left sensors, thinking there must be some residual issue, and got them painted (another 6 days in their C class loaner). It's a warranty repair, but I am getting quite tired of it.

The problem reoccurred before I got the car home - I even took a video.

Has anyone had this problem and got it fixed, or got a suggestion?
 

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Outstanding Contributor Always Remembered RI
Zotye Auto 1.5T T600 2016
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Check the position of your front license plate, if it protrudes from the front bumper too far then the sensor signal will sometimes pick up on it, had a few like this and simply pushing the edges of the plate back slightly fixed the issue.
 

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Discussion Starter #3
Great input. I shall try removing the plate for a while and see if the problem disappears.
 

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Discussion Starter #4
Check the position of your front license plate, if it protrudes from the front bumper too far then the sensor signal will sometimes pick up on it, had a few like this and simply pushing the edges of the plate back slightly fixed the issue.
I removed the front license plate altogether for a test. It's a German vanity plate, none needed in PA.

Two days and so far, so good, no false positives. Eric, thanks for the tip!

In a few more days when I'm sure the problem has not reoccurred I shall fix the plate back on and experiment with the tension and curvature, and check for vibration.

This summer I shall be in Europe and will look into getting an OEM EU front plate holder.

Thanks again!!
 

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Discussion Starter #5
Just an update, nothing more from the Parktronic, so the license plate holder was the culprit.

I asked about a euro license plate holder and my service advisor said they don't have Parktronic in Europe, but I saw some S Class vehicles this summer that had the sensors. Didn't get a chance to visit a parts dept though. I'll post back if I get one with results. Meanwhile my vanity plate was from europeanplates.com it looks like they provided a standard plate instead of a brand specific plate, so perhaps they have found the problem already.
 

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Outstanding Contributor Always Remembered RI
Zotye Auto 1.5T T600 2016
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Just an update, nothing more from the Parktronic, so the license plate holder was the culprit.

I asked about a euro license plate holder and my service advisor said they don't have Parktronic in Europe, but I saw some S Class vehicles this summer that had the sensors. Didn't get a chance to visit a parts dept though. I'll post back if I get one with results. Meanwhile my vanity plate was from europeanplates.com it looks like they provided a standard plate instead of a brand specific plate, so perhaps they have found the problem already.
I have many customers here with German built 221's and they all have parktronic, so not sure what your SA is on about.
 

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Outstanding Contributor Always Remembered RI
Zotye Auto 1.5T T600 2016
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any ideas on why this may happen in the back, even with new sensors?

thanks
New sensors have to be painted prior to fitting, make sure the correct paint was used. Also make sure all sensors are flush with the surface of the rear bumper, they are easily dislodged from their plastic clips.
 

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when you say correct paint? you mean?

I had a reputable touch up paint company mix up a spray can with my color.

I used 2 or 3 color coats and 2 clear coats. could this be the problem?
 

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Outstanding Contributor Always Remembered RI
Zotye Auto 1.5T T600 2016
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when you say correct paint? you mean?

I had a reputable touch up paint company mix up a spray can with my color.

I used 2 or 3 color coats and 2 clear coats. could this be the problem?
Sorry I do not work in the paint shop and do not know the exact details but I do know that the wrong paint can cause problems, and at a guess the clear coat could cause a problem.

From what I understand our chaps simply use one coat with no clear coat.
 

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rear parktronic

It happens to my 2009 quite frequently. I've noticed the rear headliner mounted red lights have two red dots on each side when I get the message:
Parktronic unavailable - see owners manual.
I purchased the car in June and think they probably did some kind of touch up to the bumper - is there a solvent or cleaner recommended to "clean" the sensors?
 

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bloody hell, stripped all the paint off the sensors, did one light color, one light clear, made sure they were in all the clips and still with the false readings.

I'm running short on ideas here.
 

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Outstanding Contributor Always Remembered RI
Zotye Auto 1.5T T600 2016
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bloody hell, stripped all the paint off the sensors, did one light color, one light clear, made sure they were in all the clips and still with the false readings.

I'm running short on ideas here.
The only thing you can do now is have the sensors tested using SDS, maybe one or more of them is ultra sensitive.
 
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