I have a E300 Turbo Diesel (1999) with 68000 miles.

yesterday I replaced the battery after it died....jumped it once and couldn't be jumped again, so i replaced it.

the new battery works fine, so no problem there.

now I have a check engine light thats on and the remote key will not unlock/lock my doors. I have to manually open the door with the key.

additionally, i have played with the gas cap without any results.

any reason why the battery replacement caused the remote key to not function as well as the check engine light to come on?

 

did you jump the car correctly? Could have blown a module.

 

it jumped just fine, no issues there

 

My guess is when the bat was disconnected you lost some setting. Normally when I pull a battery I use a 12 V small motorcycle bat to keep 12 volts on the system. If your car has the back up battery and it was dead also you might have to have a reprogram from the dealer.

It should be a simple $$ fix. But don't worry I dorked up my FSS setting on the maint. I bumped the button while driving when the confirm setting was showing. What ever it was for. I went from Service D in 3000 miles to over due service F by 6000 miles in the push of a button on a low milage car. So I plan to drive for 3000 miles then take it and see if that can be fixed. Perhaps we could bring them in together. I am sure both will be a free fix. $$$ Jim

 

https://mbworld.org/forums/mercedes-tech-talk/140602-help-how-reset-e55-after-dead-battery-misfire-check-engine-light-etc.html

That thread may shed some light. I had a similar problem.