Took this part to my Mercedes Dealer to install. The technician told me that it didn't work, so it was defective. He also told me that you can't trust the Chinese parts to work correctly. I asked him why it had the German name Bosch on it. He told me that they can be made cheaply in China then the Bosch name put on it. Some of these work, but many won't work in a Mercedes Automobile. I called the supplier and told them about my problem. He told me they don't have any control over who or what country makes these parts. I do plan on sending the unit back to the supplier.