[W212] Catalytic Converter clogged - Check Engine ON

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Sounds like the mythical Italian tune-up. :)
Not really mythical - the cat spent too much of its life never getting properly hot. It needed a fast run to get it hot enough to properly burn off the crud.
 
status update

after last quirk it just works. It’s been couple of weeks with no issues. Why? Have no clue. Just hope it last longer. And all these in city traffic only.

fingers crossed 🤞🏻
 
This is hilarious. I was just saying that all works and now boom check engine back again 😂😂
 
coming back with a bit of an update. short story... light keeps coming on and off and sort of got used to it

long story... it disappeared by itself (usually 1-3 days); the thing is that one time when it went on i was literraly out of power, engine almost stalling and had to drive very carefuuly. on top of that the light was blinking not staying solid. it went off again that evening then and all worked as it should. highway long drive, back on with no change in behaviour; back off and so on. what's strange is that i can't make a pattern to it. and also last two times it had no change in behaviour of the engine when it went on. very strange.

i'd go and actually change things but i don't wanna put couple of thousands just to see it make the same.

some observations maybe anyone has a hint
- don't know if it's because of winter but looks like the exahaust is showing more gases; don't know if it's just because of the hot gases coming out and creating the effect or not. tried to look at other cars and don't quite see the effect; saw something similar on a Porsche SUV and some other cars occasionally.
- have a feeling that the car gets hotter "under"; don't ask me why and I don't know how to explain; jsut when i open the door feels like a lot of heat sometimes

any advice would help. the guy at the dealership told me it's not worth putting money in this car, but i love this one so hope to get all things fixed and finally go for my tow bar and caravan :)
 
coming back with a bit of an update. short story... light keeps coming on and off and sort of got used to it

long story... it disappeared by itself (usually 1-3 days); the thing is that one time when it went on i was literraly out of power, engine almost stalling and had to drive very carefuuly. on top of that the light was blinking not staying solid. it went off again that evening then and all worked as it should. highway long drive, back on with no change in behaviour; back off and so on. what's strange is that i can't make a pattern to it. and also last two times it had no change in behaviour of the engine when it went on. very strange.

i'd go and actually change things but i don't wanna put couple of thousands just to see it make the same.

some observations maybe anyone has a hint
- don't know if it's because of winter but looks like the exahaust is showing more gases; don't know if it's just because of the hot gases coming out and creating the effect or not. tried to look at other cars and don't quite see the effect; saw something similar on a Porsche SUV and some other cars occasionally.
- have a feeling that the car gets hotter "under"; don't ask me why and I don't know how to explain; jsut when i open the door feels like a lot of heat sometimes

any advice would help. the guy at the dealership told me it's not worth putting money in this car, but i love this one so hope to get all things fixed and finally go for my tow bar and caravan :)

this sounds exactly the same as what i’m currently having with my A35 AMG, I wrote a thread about it today in fact after coming back from France and having this issue on the motorway. I was thinking it could maybe be the injectors as I noticed every time I reach 3/4 - 2/4, that’s when it becomes worse but on a fuel tank you can pretty much pass through 3000rpm with ease. My car is 6 months old and is already doing this... maybe because I drop up and down mountains a lot and the difference in atmospheric pressure killed the Catalytic converter? Or maybe it’s something to do with fuel not getting in (I.e injectors not working)
 
Modern gpf dont like being left idling for very long periods of time, they can be regened via diagnostic equipment but its very far and few between, i have only ever had to do 1
 
I would have it deleted and remapped. Or get it off the car open it up..scrape the inners out (what's left) weld back up and re-fit.
 
Do the E500s have this trouble?
Seriously wondering if I should sack off the E350 CDI for a petrol. Was thinking about the W350 CGI, but this is making me wonder if the E500 is the way to go?
 
Guys... Just to clarify... Had the light in and off several times... Went to another Mercedes authorized service and they said the cats are ok. They suspected fuel pump but on diagnose it was a fuel regulator. Exchanged that one and in 3 days it happened again. Final conclusion: fuel pump NOK. So the worse happened. Replaced it and all good by now. They said they found the oil level at half which is insane for me as i had no warning in the dashboard except the one that says in white to check next time you stop. It's hard for me to believe that but They say this might have caused the failed pump as well
Anyway now all it's ok on this side.
 
It's been 6 months or more but thanks for getting back to us :thumb:
 

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