I pluged in a code reader today as my car has been juddering at 3000 rpm and wont go past 3000 rpm i got fault code p0141 for 02 lambda sensor bank 1 sensor 2 witch one is this the pre cat sensor or the post cat sensor? The car does have a de cat tho so is there any chance thats why i am geting the fault code.? Also would a dodgy lambda sensor cause the juddering problem?. Any help would be very greatful. Thanks