here in tx you are allowed to have at least two monitors "not ready".i would assume that if the cat is not ready that the before and after o2 sensors are not showing the ecu an attained level of efficiency.maybe if you warm up car and use a scanner to read the before and after sensors you may get an insight into the cause.maybe something simple like the o2 heater in the rear sensor not operating.[blown fuse or bad connection]

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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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