Originally Posted by waiter21
Some codes (most) will auto clear the Check engine light but remain in memory for some time. Then given enough start cycles, they will clear out of memory.
i.e. the famous Evap slow leak P0422 will clear itself if the OBC successfully completes the entire Evap canister purge cycle and doesn't detect a leak. This code is usually set when you forget to put the gas cap on.
The OP posted in the MB forum to discuss MB Sprinter issue. It is best to stay vehicle specific in posting, based on your MB knowledge in the area of the OP topic. Otherwise, the thread becomes poluted with mine (ford chassis) does this. Not constructive to the OP's original intent. In learning, your post on the "mode 6" was very informative. I assume all OBD II computers have a mode six retention, although I do not know for sure. The problem occurs when certain manufacturers, try to make some facets of the diagnostics proprietary, just not sure in this case however. Just sayin'