Domislo1993

Hello everyone, so I have an issue with my C220 2018... I have a yellow check engine light on constantly with 0 error codes. Been to the dealership twice, never found a problem. Now, the car has already 393.000 km on it so I'm guessing it could be catalytic converter, but should it be shown under error codes? Also, the car stopped using Ad Blue (level of fluid staying the same all the time). This is becoming quite annoying as I cannot locate the issue (with any reader).

Any help/insights would be much appreciated.

Thanks in advance,
Dom

PaulR7

Spitballing here but did you (or is there a chance a previous owner) have the ECU remapped, possibly with one of the many options such as EGR and AdBlue delete? Most of those tunes/options also should disable the CEL for the lack of those systems but it might have thrown it out as a hiccup.

Domislo1993

Did talk to him, said nothing of sorts was done to the computer so this shouldn't be a problem.

I still have to check all the fuses, you think this might be the problem?

Also thinking it might have to do something with any of the sensors like MAF, but then I'm guessing it should show me some codes, yet nothing... Car runs fine, just the light is super annoying.

matt.jessop

Buy a basic ODB2 code reader - that will give you a code which you can then google. You can also reset the CEL.

I bought this one but many available -

Domislo1993

Like I've said, I have a friend with quite advanced reader and it showed nothing, as well I have taken the car to the original MB service, and their reader showed nothing as well.. Now I'm kind of blind searching the internet to find and possible solution hmm :/

matt.jessop

Ah apologies I missed that ! Good luck - its very strange !

Domislo1993

Thanks brother for your input, I appreciate it really It's just so frustrating.. Some say it may be gas cap, but it's fitted well and in good shape, then some it may be air intake filter too dirty but it's fine, then some that a fuse might have blown or MAF sensor, or catalytic converter etc... Trying to not get into expensive nightmare haha

Domislo1993

SOLVED!!

Funniest thing ever. It seemed that the Ad Blue tank was overfilled, which it made sensor not working properly, thus showing the same milage all the time + it created a vacuum in the tank bc of the overfilling and could not push ad blue further. Cel light came on, but there wasn't any error code because everything was working normally except for emissions which were too high.

Emptied the ad blue tank, made a reset of the car, then I put in new ad blue (20l), turned on and it worked like a charm.

Hope it helps anyone in the future.

Dom

matt.jessop

Wow, well done in finding that ! Glad you got it sorted

Andy74

How did you identify the issue? Glad it is sorted out for you. Thanks for sharing.

CaliBenzDriver

How many live modules can the reader you tried effectively worked with?

Some people report good success with "iCarSoft MB" scanners

This time it was DEF sensor, next time...