There are some faults caused by car adaptation or refitting, and we will share a case caused by putting protective film on windshield. Check below fault symptom and diagnose process.

Vehicle information

Model: VW Passat

Year: 2019


Fault symptom

The keyless entry function is no use and the car won’t start.


Diagnose process

1. This car uses the keyless entry "KESSY" system. When approaching a certain distance of the vehicle, the car will recognize the chip in the remote key to unlock the door lock and release the anti-theft. When leaving the vehicle, touch the outside handle of the door, the door will automatically lock and enter the anti-theft state.

2. The faulty vehicle cannot achieve the above functions, and the door cannot be locked normally by using the remote control. After entering the car and turning on the ignition switch, the dashboard displays a message "no key found in vehicle", and the engine cannot start. It can be preliminarily judged that some functions of the "KESSY" system have failed.


3. Connect scanner with car, read fault code: 00470 –combination comfort databus in single wire.

4. Because the car is a new car, the customer had this problem immediately after getting the car. It was suspected to be due to refitting or adaptation. Before that, the car had just been put protective film on front windshield. Then check the KESSY control unit and unplug the KESSY control unit and found some water on there. When examining the cause of water ingress, it was found that the car was doing a front windshield film. When it was filmed, it was necessary to spray washing water on the inside of the front window glass. Without protection, some water entered the KESSY control unit along the internal wiring harness of the dashboard. Clean the plug and replace the control unit with a new one. The fault disappeared after online coding.

5. In response to this problem, we should focus on asking what work the vehicle has done before and whether it is directly or indirectly related to the occurrence of the failure. This may play a vital role in judging and rectifying the fault, which can reduce the time to find the fault point as soon as possible, improve the maintenance efficiency, and reduce the technical damage.


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