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Troubleshooting Mercedes Parking Sensor Parktronic Problems

This article provides instructions on how to troubleshoot Mercedes Parktronic (not to be confused with Active Parking Assist).

Troubleshooting Mercedes Parking Sensor Parktronic Problems
ESTIMATED TIME 30 min - 2 hr
DIY COST $0-$100
DIFFICULTY Intermediate

Learn about common problems and faults Mercedes owners often experience with the parking system. How to replace Mercedes parking sensors yourself. 

How does the Mercedes-Benz Parktronic system work?

mb parking assist parktronic system


The first generation of Mercedes Parktronic system uses sensors on the bumper to detect objects nearby. It provides a visual and audible warning as the distance between the object and the car decreases.

The park assistance will only work if the vehicle is in drive or reverse, and the Emergency/Park brakes are released.

  • If the transmission is in Drive, the front warning indicators will be enabled.
  • If the vehicle is in Reverse, the rear warning indicators are enabled.

The Parktronic system starts to beep as you get close to objects. The beeps and tone frequency start to increase as you get closer to objects in front or back of the car.

Mercedes Parktronic system does not work at speeds over fifteen mph. The system will automatically turn off and get enabled again when you slow down. The system is deactivated if you set the shifter to Park.

Common Symptoms

  • Parktronic beeping constantly
  • Red LED indicators are on all the time.
  • Mercedes parking sensors are not working.
  • Two yellow lines are always on at low speed.
  • Beep when you place the car in Reverse
  • Random beeping from Mercedes parking sensor
  • Parking Assist Malfunction
  • Mercedes Parking Assist is not working.
  • Mercedes park assists inoperative.
  • Mercedes parking sensor keeps beeping.

Mercedes Parktronic Problems

mercedes parktronic system


If there is a fault in the system, you will need a Professional Diagnostic Scanner to diagnose Mercedes systems.

mercedes parktronic fault


When you read the fault codes, you may get error codes such as:

  • B8/8 Inner rear right DTS ultrasonic sensor error
  • 9023 / B1023 / 36899 Parking System Fault
  • B1248 B1252
  • 9005 A42B2 Left Center Sensor. Front Bumper. The sensor is not properly fastened, assembled, or there is an obstacle near the sensor.
  • 9042 At the control unit, the supply voltage for warning elements is outside the permissible range.
  • 900E A42B5 Right center sensor, front bumper. The sensor is not properly assembled, or there is an obstacle.
  • 901A A43b9 Left inner sensor, rear bumper.

Common Causes

  • Unplugged parking sensor
  • The parking sensor has poor contact or is loose.
  • A sensor or cable is faulty or has high resistance.
  • The sensor is missing or damaged.
  • Wiring issue
  • Blown fuse
  • Bad ground connection
  • Damaged parking sensor due to water intrusion
  • Rain and dirt on the parking sensors

Troubleshooting Steps

mercedes parking assist problem


It is simple to spot when only one of the parking sensors on a Mercedes-Benz is defective. You will see one of the warning bars always lit up.

You need to check the sensor that corresponds to the bar that always stays lit up. The bigger challenge is what to do when the Parktronic system doesn't work at all. Below you will find a few items that you need to check when Mercedes Parktronic doesn't work at all.

Check Parktronic fuse

mercedes parktronic problem fuse ok

Check the fuse for the Parktronic system. In most cases, the fuse for Parktronic will be in the fuse box found in the trunk. The fuse is labeled Parktronic and typically is a 10A fuse. If the Parktronic fuse is not in the rear fuse box, check fuses on the dashboard's side, under the rear seat, or in the engine bay.

Check Power Supply

Use a digital multimeter to check for power at the Parktronic fuse.

Check Bumper Sensors

mercedes parktronic bumper sensor

Remove the bumper and check the wiring on the back of the sensors. Make sure all the sensors are plugged in.

None of the wires are damaged or cut due to an accident or previous repair work. Unplug the electrical connector and check the terminals/pins on the sensor for corrosion.

If you are missing one of the sensors, replace it with a genuine Mercedes Parking Sensor.

If you are expecting problems only when it rains, water is getting into one or more of the parking sensors and causing that certain sensor to stop working.

Check Parktronic Switch

mercedes park sensor parktronic not working turn off

The Parktronic switch can get sticky or stop operating. You may want to go further and remove the switch to check the operation with a multimeter.


If the range of your Mercedes-Benz parking system is poor, clean the sensor first.

In the following video, you will learn how to troubleshoot Mercedes-Benz Parktronic using an all-system OBD2 scanner. Basic OBD2 scanners can not diagnose the Parktronic module. 

If the sensor still doesn't pick up objects until you get close, identify which sensor is not picking up the object. Front or rear? Left or right?

You can't adjust the range of the parking sensor. If the sensor is faulty or not picking objects, it will need to be replaced.



Is there a way for this stupid system to be auto-turned off. I hate having to press it each day, and multiple times a day, to turn it off if I take the key out of the car. If you live in any tight city, it is going off all the time and the beeping inside, is worse then the honking, outside. I can't seem to find a way to default it to 'off' though...


Our parking sensors go off and flash red on the far right panel every time I press the footbrake. A continuous beep for about 8 seconds and then goes off. The same thing happens every time you press the brake.... Driving us nuts!!!


Great info. However I don't see any mention to the buzzer volume. I recently came across a car where the rear Parktronic had very low buzzing sound while the front system had a clearly audible sound. Can the sound o the buzzer adjusted?


The local MBZ dealer quotes me $600 to replace on front sensor. Is this reasonable or robbery?


The bleep seems to start VERY late in the process. Can the range when the bleep starts be adjusted?????
A robbery for sure, especially if you owned a simple Toyota or Honda before. However, spending $600 on something as simple as this is common for Mercedes owners. It's best to try and learn to do these simple things ourselves to save thousands over the years
I think a bad fuse is probably one of the most common causes of this issue. However, where can we find these? If we want to do this ourselves and not to go to an expensive dealership?
Hi, I have a 2016 b200 My Parktronic wasn't working on the driver's side so I went to the local Mercedes garage at Pontypridd they gave it a diagnostic test and said the battery was faulty and advised me to have a new battery I had it changed at a cost of £337 pounds when I came away I tried the Parktronic and it was still the same I went back and complained and the boss went for a test drive when he came back he said it was working fine as it should be because Mercedes has set it up so that it only works on the near side is this correct?

Nas Khan

Red LED indicators on all the time on the rear. the front work fine. I have had this issue intermittently for a while, now its continuous. I have an ML350 164. I'm going to check it out now. I presume it can't be all the sensors at the back so maybe wiring or rear sensor module, if it exists. Is there only one parking sensor module for front and back are there separate front and back? Many thanks.


Parking sensor error code B2125-00. Parking sensors are not working! Car is a 2015 A45 AMG


Hi Folks, got a sensor problem with no 4 sensor my friend checked and it came up with Code B1253-23 / parktronic sensor 4 has a malfunction. no signal change: Voltage level is low.- current stored. Code B 1253-24/ Parktronic sensor 4 has a signal change: Voltage level is too high.- Stored

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