1999 Cadillac Catera base 120k.
Just changed all spark plugs and coil packs for both banks. Cleared all codes and
lights.Car ran great for 1 week and now check engine light is back on and codes for both
banks running rich are shown. Car idles and drives perfect even with light on, and mileage
is down. Any suggestions?
http://www.obd-codes.com/p0172 - check this out for possible causes and solutions.
http://www.obd-codes.com/p0175 -- they both the same just different bank.