Numerous problems with my 05 C230


2. Persistent P0420 code ever since I installed the Kleemann header/cat, even after replacing the pre- and post-cat O2 sensors.
3. Oil on spark plugs (seems to be common as seen in other threads) and in intercooler.
4. Belt tensioner is bad (belt squeals). I already changed the idler pulley and belt.
I have to get my car emmission tested this month, and it won't pass if my CEL light is on.
Last edited by capt_paul; Aug 31, 2009 at 01:57 AM.
I know you're venting. It's not that drastic, though.. just be glad you don't have a 2001.


The P0420 is perplexing because the code always trips at a minimum load (~28%) at 65-70 mph around 2700-2800 rpm. Could it be a cheap cat that Kleemann provides for its header? Luckily, I have my stock exhaust /cat. I will have to buy a new intermediate pipe though, which is very expensive.
The serpentine belt only squealed when first putting a load on the engine (as in putting it gear from park or reverse) with the ac on. When the ac is not on, there is no squeal. Luckily, the compressor (perhaps the whole repair) will be covered under the Indy shop's 1=yr warranty. After changing the belt and the idler pulley, it only leaves the tensioner assembly to blame. According to the repair manual, I have to remove the supercharger and the intake manifold in order to get to one bolt behind the tensioner in addition to the ones in front.
I just want the nightmare to end.


I tried to find a O2 spoof, but for Mercedes cars, there is nothing available due to the car's impossible ecu nannies.
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I'm still getting the P0420 with my cat too, but only if I've been driving for a while. So when I get my car inspected on Friday, it will be fine. However, a longer-term solution other than clearing it every time it comes up (though with my Scangauge II in the ashtray, it's about a 5-second fix) would be great.


Kleemann is working with me to resolve the issue with the P0420 code.
Dropping off the car for the AC repair (covered under warranty)
Tensioner- still debating on doing it myself, indy shop, or dealer.


I'm still getting the P0420 with my cat too, but only if I've been driving for a while. So when I get my car inspected on Friday, it will be fine. However, a longer-term solution other than clearing it every time it comes up (though with my Scangauge II in the ashtray, it's about a 5-second fix) would be great.
If and Kleemann do resolve things, please post it up. Thanks.
one thing to note: drive the car a lot say 1k+ miles before you go have the smog test. reason is that whenever you get a CEL or disconnect the battery after it's reset the ECU needs a lot of miles before it would register everything as running normal.
Last edited by FrankW; Aug 31, 2009 at 05:53 PM.


I think the codes that are captured are shown as pending first, before it goes to a hard CEL.
I have to get my car smog tested by the end of this month, so I hope everything goes well.


The comment on the tranny is interesting. I have a manual with the Kleeman headers, too, and only get the P0420 code about every 3 months or so. Not sure how the tranny might affect it, although I rarely let my car idle without revving it a little. That may prevent the computer from running the rich/lean checks (which are done at idle, I believe). I doubt many people would regularly rev an automatic at a stop light. I also have a very short commute, which may not allow the engine to warm enough for the computer to run the check (although I do enough warmed-up driving that I doubt that is it).
And as noted above, if Kleemann finds a solution, please post it.
1k miles seems excessive to me.
My car gets all readiness adaptations set within 100 miles.
edit: actually it was about 200 miles of city/highway driving
Last edited by Dingleberry; Aug 31, 2009 at 11:54 PM.









