Just read out the error memory of the car at home? This is possible with OBD2 diagnostic devices. We tested eight devices from 30 to 84 euros and compared them with an expensive candidate for 380 euros.
The engine indicator light is lit – if there is a problem, the car communicates this via appropriate indicator lights in the cockpit. But as a rule, the driver is at a loss in front of the flashing indicator. The engine indicator light alone indicates a large number of faults – from the defective valve of the exhaust gas recirculation to the defective ignition system, countless problems can be behind it. To find the exact cause here, only one thing helps: read out the error memory of the car. All petrol engines registered from 2001 and diesel registered from 2004 onwards have an OBD2 interface.
Some manufacturers have also introduced the standard much earlier (e.B. Volkswagen from 1996). For reading, a corresponding diagnostic device is connected to the OBD2 port of the car, which reads out the ECUs and spits out all error codes. These should then provide the decisive clue for the error. However, our test shows that especially cheap devices for laymen often do not fulfill this purpose one hundred percent.
Only a cheap diagnostic device convinces
In order to read out the error memory at home, there are a variety of products at different prices. Depending on the selected depth of the diagnostic tool, there is a wide price range from cheap products around 20 euros to premium devices for private use around 300 euros. AUTO BILD has tested eight inexpensive devices from 30 to 84 euros and competed against a semi-professional device for around 380 euros. All tested diagnostic devices are universally applicable, which means that they can read the vehicles of each manufacturer. However, they have problems with manufacturer-specific codes, here only a manufacturer-specific device helps. In addition, all candidates provide a direct translation of the error code instead of just displaying the letter-number combination.
Among other things, the diagnostic devices had to find four faults each in three different cars. For this purpose, we prepared cars from our garage with typical faults such as a defective ABS sensor or a fault in the lambda sensor in advance. Result: Only one device has reliably found every fault, and that is the semi-professional diagnostic device from Launch. In the case of the cheaper candidates, the results are similar, in total they were usually able to recognize and display two-thirds of the errors. The difference between the cheap products and the more expensive device is therefore mainly in the selection depth. While the cheaper products can only read out two or three control units on a superficial basis, the launch device penetrates deeper and can read out significantly more control units of the car. The launch device can also not only read and delete errors but also code control units. But only professionals should be involved here because in the worst case you paralyze the whole car with a mistake – that will be expensive.
reference: command line mapped drives
All low-cost devices had difficulties reading out the Audi RS4 (BJ 2020). Some devices such as the BGS, Autophix, and Ancel still found a non-specific error in the dynamic control unit, which is at least an indication of the ABS. But only the launch could really help satisfactorily here. There were also minor problems with the VW T-Cross (BJ 2020) and the Mercedes E-Class (BJ 2007). Here, the low-cost devices were able to read out three out of four errors. A removed ABS sensor (T-Cross) and an airbag fault (E-Class) were not found by any cheap product. Here again, only the Launch 129 Evo could read out the errors. Due to the significantly larger range of functions and the high price, however, the device was tested by Launch out of competition.