Tuesday, April 26, 2016

Strange problem with Mercedes A150 (W169)

Two weeks ago I have got a strange problem with my Mercedes when driving in the city. The car started losing power until it stopped. Board computer showing "ESP Problem" and engine running between 1200-1800 RPMs as seen on that short video:


I have tried to find any information on the Internet with no result. In general, there is almost no technical info for that model of A-Klasse.
Using ODB2 scan cable and software I found two errors, pointing to the throttle valve: P2118 and P2119. No other errors recorded.
What I did next was to take the throttle body out of the car, following these steps:

1. Disconnect the negative line from the car battery!
2. Remove the air filter and ECU from the air filter body.
3. Disconnect the vacuum compensatory tube (part of the braking system) from the side of the engine.
4. Disconnect the airway tube between the air filter body and the front bumper.
5. Remove the air filter body.
6. Disconnect the cable for the throttle valve and removing the valve.



The valve was blocked with a lot of tar-like substance and was not mobile. Cleaning it did not make it move at all, just cleaner :) Then I have decided to check the mechanical part of the throttle valve by removing the plastic cover of it. After the cover was removed, I saw the reason for the problem - the marked with red gear has few smashed cogs, blocking the movement of the valve. Fast check at the local Mercedes Benz dealer, resulted in 800EUR price for a new throttle body.

As a temporary solution, I have taken the gear out a little - just to be possible to free spin it and turn it with few degrees, enough to pass the broken cogs and go on the good ones. That's a very temporary solution with risk more cogs to break and with potential problems when the valve should be fully opened.


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