Troubleshooting Mercedes Parking Sensor Parktronic Problem, Cost, DIY Replacement

Troubleshooting Mercedes Parking Sensor Parktronic Problem, Cost, DIY Replacement

Updated Thursday Dec 14, 2017

In this article, you will learn how to troubleshoot Mercedes Parktronic (not to be confused with Active Parking Assist). Common problems and faults Mercedes owners often experience with the parking system. How to replace Mercedes bumper parking sensors yourself. Which by the way is very easy and you can save hundreds of dollars by doing yourself.

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1. How does Mercedes-Benz Parktronic 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. 

Parking assist only works if the vehicle is in drive or reverse and Emergency/Park brakes are released.

  • If the transmission is in Drive the front warning indicators are 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 frequency of the beeps and tone 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 15 mph. The system will automatically turns off and gets enabled again when you slow down. The system is deactivated if you set the shifter to Park. 

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2. Common Symptoms

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

mercedes parktronic system

If there is a fault in the system you will need a diagnostic scanner that can diagnose the Parktronic system.

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 include:

  • Unplugged parking sensor
  • Parking sensor has poor contact or is loose
  • Sensor or cable is faulty or has high resistance
  • 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
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4. Troubleshooting Mercedes Parktronic system that doesn't work

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. In which case 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.

1. 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 side of the dashboard, under the rear seat or in the engine bay.

2. Check for power

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

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

4. Check the operation of the Parktronic switch

mercedes park sensor parktronic not working turn off

The switch can get sticky or stop operating. Remove the switch and check the operation with a multimeter.

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5. How to replace Mercedes parking sensors

Mercedes parking sensors can fail causing part of the system to not work properly. Failure is either due to accident or the sensor may stop working if water gets inside it. You can also remove the sensor and try to dry it but it doesn't always work. Replacement sensors is very cheap and can be bought online for $20-$30. OEM, aftermarket or used original Mercedes parking sensor all seem to work fine. Click here to check current price on Mercedes bumper parking sensor.

What you will need

Mercedes bumper parking sensors are interchangeable between models. 

PTS Parking Sensor for Mercedes-Benz

mercedes parking sensor
  • Mercedes Parktronic Bumper Sensor
    • The same sensor is used on multiple models including C S E CLK SLK CL M ML G GL R Class. 
    • Part numbers: A2125420018
    • W203 W209 W210 W211 W220
      • 0045428718 / A0045428718 / 0263003556 / 0015427418 /A0045428718

Always verify compatibility with the auto parts seller or dealer. 

Matching Paint

mercedes matching paint

New Mercedes parking sensors typically do not come painted. Therefore the new sensor will not match the paint of your bumper and car. Getting the new parking sensor to match the color of your car is easy. You will need to get a custom mixed spray can that matches the color of your Mercedes-Benz. Local auto body paint shops often sell custom mixed paint. All you need is to provide the paint color code of your Mercedes-Benz. Mercedes paint code can be found on the sticker on the driver's door.

mercedes paint code location

It is on the right side the label. It will end with three numbers. For example 744 which is commonly silver or 040 for black.


Replacing parking sensor on a Mercedes-Benz is very easy. In this guide, we will show you how to replace a Mercedes parking sensor but also how to paint the new sensor to match the color of your car.

  1. Get a new Mercedes parking sensor. It can be used or new. If the sensor matched the color of your car great. Skip the painting steps. mercedes bumper parking sensor


  2. Sand down the old paint from the sensor. If the sensor is not painted, scuff the surface with 500 grit sandpaper. diy mercedes parking sensor


  3. Spray a light coat on the sensor and let it dry for at least 15 minutes. Apply a second coat of paint. If you are using single stage paint it will contain clear as well. But if you would like to have the sensor look as close to the original bumper, you can apply a coat of Automotive Clear mercedes aprking sesnor replacement painting to match color


  4. Determine the faulty or missing parking sensor. missing mercedes parking sensor


  5. You will need to access the sensor from under the bumper. mercedes parking assit sensor replacement


  6. Unclip or remove any bolts that hold the bumper in place. Mercedes-Benz uses plastic retainers and 10mm bolts but in some models, Torx drive bolts are used.remove bolts to replace mercedes parktronic parking sensor


  7. Reach to the back of the bumper and remove the sensor by pressing the two locking tabs. mercedes pts sensor


  8. Press the new sensor in place and plug in the electrical connector. 

5. Read codes from the Parktronic control unit

If the range of your Mercedes-Benz parking system is poor, clean the sensor first. If the sensor still doesn't pick up objects until you get very 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.

In the following video, you will learn how to use a Level 3 OBD2 Scanner to troubleshoot Mercedes-Benz Parktronic. Note that diagnostic can also be performed with Level 2 OBD2 Scanner that is designed for Mercedes-Benz cars such as iCarsoft MBII which is a cheaper alternative. 

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6. Additional Resources

  1. How to replace parking sensor on Mercedes S-Class W220
  2. Pictures of various Mercedes sensors 
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