Audi Q3 Start-stop System Can’t Work

Audi Q3 Start-stop System Can’t Work


Audi Q3 dashboard shows that “Automatic start-stop system failure! Function unavailable”. Use vas5054a to do the trobleshooting and solve the problem.
There is a 2013 Audi Q3 SUV which has 2.0 LCRHA engine, and has run 16,000 km. The customer says the central display screen of dashboard shows that “Automatic start-stop system failure! Function unavailable”.

First, confirm the trouble. Connect VAS 5054A diagnostic tool to read the trouble information in engine and the dashboard control unit, no trouble record. Using VAS 5054A to read the engine control unit “read Start-stop historical data”.
 
Get another car which has the same configuration. Read the code of engine control unit and compare it with the repairing car. I find the 5th byte code of repairing car engine control unit is 5 F. And this stock car is 4 F. Correct the code of repairing car engine control unit. Test it, the trouble still exits.
 
Ask the customer whether the car equipped with other equipments. The customer says, the car added a reverse image and a car cat system. Read the match data of engine control unit. And compare with repairing car, I find that the data in matching channel 19 and 23 is different from the stock car. The data of matching channel 19 and 23 in stock car engine control unit is 1. But the repairing car is 0. Then, change the data 0 (in the repairing car) into 1. Testing the car, the trouble is dealt with.