2002 X5 3.0l has engine light on, had dealer check for code and they said it was PO420 "Catalyst System Efficiency below threshold"
They said that the vehicle appears to have aftermarket Cats on it and the O2 sensors do not like what's coming at them. They wanted $1500.00 per side to replace them. I brought it home and checked myself as I just got the EV 327 OBDll scanner, it verified the code!
I noticed the readings on one bank were as follows Long term fuel trim bank 1, -2.3%, all others were 0%. Is it the aftermarket Cats causing the problem or O2 sensor? Some Cats are constructed with better metal than others!
Just joined the site & love it!
Cheers
Don
06-01-2010, 10:43 PM
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