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

Table of Contents

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.