Originally posted by Bad Apple:
ran the old tester on it again, error code p420 catalyst system below threshold bank 1. CEL doesn't come on. bank 1? wtf? it's not the first o2 sensor is it?
Bank 1 / 2 seems to mess people up
Bank 1 = bank with cylinder 1 in it
Bank 1 = right hand bank
Bank 1 = you need a third elbow to get to it 'cause it's by the firewall on your Duratec powered Contour/Mystique/Cougar
I just got done chasing a bad catalytic converter on bank 2 (front of Contour). Same code, it wasn't the O2 sensor this time though. The cat is bad, it's getting to be plugged up, power is down, so it's gotta go. And, lo and behold, right about the same time the flex pipe split, so that's going too. Major fart pipe sound from the ATX, sounds kind of unrefined.
You may be able to "fix" this by replacing both the upstream and downstream O2 sensors on the bank (96+ only has two sensors, 95's which are pre-OBDII have one).
