Removing/installing the ECU is a 10 minutes process… IF you know how to do it; otherwise it can be a headache and you could end up damaging something.

I decided to write this DIY because the instructions I received from my tunner where useless. So if anyone is planning to get an ECU tune, or want to remove/install the ECU for whatever reason, here it is.

Things to know before you begin:
1. You don’t need any tools for this
2. The car needs to be cold since the ECU sits on top of the engine and it gets really hot; so don’t expect to drive home and start working right away.
3. Once you remove the ECU you will not be able to turn the car on, so do it somewhere where you can leave your car without problems. For instant, not behind your wife’s car.
4. It is advised to disconnect the battery for this procedure, although I didn’t do it and my car didn’t blow.

First you need to remove the plastic cover in front of the air box. It will pop off with very little pressure. Then you need to disconnenct the 2 intake hoses plus a third smaller hose from the air box. These are also snapped in and are flexible enough to come off without hassle.



With all the hoses off, you can now pop up the air box. I suggest you store both the air box and the plastic cover in the trunk.



The ECU is hold in place by four rubber pegs, you can now lift it up to get enough room to disconnect it.
There are two harnesses you will need to disconnect on the back of the ECU. Notice that the plastic plug where the harnesses are connected is actually part of the ECU. DO NOT pull them in any way. To disconnect the harnesses you simply pull on the plastic lock on the side and they will come off.



You are done. To reinstall is simply the reverse, be sure to snap in all four of the airbox corners and that all the air hoses are all the way in.

God bless you.

That's some good info.

Finally! Thanks for the post man!

+1

Great post!!

Next question(s), has anyone ordered a aftermarket ECU Upgrade and from where?? And was it worth it, if so?

yeah, i really want to know too, i am thinking of going to find a totalled c350 and see if i can use teh ECU so i can have it tuned

Thanks guys. I'm just glad I could contribute to the forum

Wow, I feel really dumb now because that's NOT where I have been envisioning it all this time, I thought it was under the dash near the pedals....

Awesome DIY write up! Two thumbs up!

Yep, just check the OP's other post titled "MKB ECU upgrade comming up!!"

linky

Stick This!

Question, where can you get an upgraded ecu? benefits on a c-35- auto? negatives?

I live in Germany, and I asked the Carlson tuners who handle all the MB, and they said that the series sedans will not benefit from an ECU tune, and they only do ECU tuning for the AMG. I can't imagine that it would be worthless, but that's what the MB experts here say.

it that really?

Andy

I call on that. I believe ANY stock car will benefit from a properly tuned ECU. Maybe they think owners of the smaller engine cars are not a large target group for performance upgrades and it would not be cost effective. Don't they realize WE are the ones that need the help?

Yeah, I don't have a clue why but I think they quoted me around 1600 euro for an ecu tune until they realized it was only a C350, at which point they told me they wouldn't do it. I think it might be something between MB and Carlson, because they did not seem very eager to do any work on my series sedan.

EDIT: Also, if anyone knows how to remove the speed limiter from the ECU.. I am more interested in that than the actual tuning part. My old Peugeot had a higher top speed than my new Merc!

very nice write up and easy to understand...

That was a thread hijack, starting a new thread.

Why would one want to upgrade his/her ecu?

Power. In some cases with some cars with a few or more than a few engine modifications, a tune is very beneficial as you can take even more advantage in the engine parts you put in as well is to modify the useful power range of the car.

Would pulling off the harness of the ECU reset the ECU?

why would mercedes put the ECU on the hottest spot in the engine bay

They wanted to make the hottest ECU on the market

Funny lol

All I can say is to remove the top portion of the airbox, you need to slide the silver retaining ring back first before you pull off the top.