based on your numbers i strongly suggest that you get a cat replacement.here in texas that can be done for less than 300 installed and will make a huge diff to your readings and you won't have to sweat the little stuff which may or maynot help.the reading of 15.2% co2 means that the engine is running very well.[it's a measure of efficiency] and is one of the reasons i'm saying replace the cat.the other is the high nox.just did this on a client's car 3 days ago and then passed with flying colours.

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David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
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