System description

The ParkAssistent supports the driver when reversing. The system detects obstacles and indicates these to the driver in good time. If an obstacle is detected by the system, a signal tone with a tone break sounds at a distance of 1.5 m from the inside sensors and 0.6 m from outside sensors. The tone break of the signal tone shortens as the vehicle approaches the obstacle. At a distance of 0.3 m, a continuous

System readiness

The ParkAssistent signals readiness with a short signal tone provided that:

the ignition is switched on reverse gear is engaged

System errors are indicated by the sounding of a continuous tone after reverse gear has been engaged. This continuous tone differs from the continuous tone emitted when an obstacle is

System components

The ParkAssistent consists of a control module which is located under the driver's seat together with a cover plate.

four ultra-sound sensors which are installed an audible signal transmitter which is integrated into the instrument cluster.


Danger of injury and damage to vehicle when the vehicle is rolling backwards!

> Reverse gear must be engaged and the ignition must be switched on; otherwise the ParkAssistent System is deactivated.

Danger of injury and damage to vehicle when the system limits are reached. The system does not free the driver from his/her responsibility to be careful.

> Short obstacles such as a person lying down cannot be detected.

> The reflecting behaviour of the system can be impaired by sound absorbent obstacles such as powder snow or sound-reflecting obstacles such as glass surfaces.

> Very thin obstacles and obstacles with no reflecting surfaces cannot

Every sensor emits an ultrasound beam with the following geometric specification.

horizontal beam width = 120°

vertical beam width = 60°

The control module measures the distance between the sensor and the obstacle at cyclical intervals. The measurement is based on the echo depth sounding principle. The sensors are activated in regular intervals for a short period of time and emit ultrasound waves. Then the sensors are switched to reception and collect the reflected soundwaves. The control module then calculates the distance between the sensor and the obstacle from the running time of the soundwaves.


The following components are monitored at cyclical intervals with the ignition switched on and reverse gear engaged.

Control module supply voltage

Sensor supply voltage

Functioning of all sensors

Functioning of control module (transmission and reception pulses, EEPROM)


External weather conditions such as ice, snow or dirt can impair the functioning of the sensors and result in an error.

The four sensors are connected to the control module by a wiring harness installed in the rear spoiler. The rear spoiler must be removed to replace the sensors or take measurements.


Disconnecting the plug from the sensor

If a sensor must be replaced, the electrical plug connection must first be disconnected.


1. Raise the lower tab gently with one finger.

2. Pull out the plug.

Soiled or frost-covered sensors lead to malfunctions in the system. However, in this case the errors are not stored. Instead, the same continuous tone is emitted as for obstacle detection. When the cause has been eliminated, the system returns to normal state and the continuous tone is no longer emitted.

91 . D 44 91 01 Diagnosis/troubleshooting ParkAssistent (System P 01)



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