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P0420 Diagnostic Trouble Code Discussion for February 2008

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1998 Mazda Millenia S 2.3L MIL Lamp on VIN: JM1TA2224W
P0420: Catalyst Efficiency Below Normal (Bank 1). Vehicle has what appears to be a classic converter efficiency issue. What puzzles me is when watching both the front and both the rear O2 sensors on my Modis in scope mode, it appears both rears are switching almost identical to the fronts yet it only sets a b...
February 06, 2008
1997 Toyota Camry CE 3.0L MIL Lamp on VIN: JTW294I573
P0420: Catalyst Efficiency Below Normal (Bank 1). hello toyota techs, i have this 97 camry with mil on for po420 cat eff low. cust states it was at another shop 3 month ago, was told it needed a new cat, but tech cleared code . not sure if it was a 420 or not, but it took 3 months for it to come back on. it c...
February 06, 2008
2002 Subaru Outback L.L. Bean 3.0L MIL Lamp on VIN: 4S3BH80642
P0420: Catalyst Efficiency Below Normal (Bank 1). Code for catalyst efficency on bank 1. (Passanger Side) Replaced front pipe with oem and light reoccurred. Rear cat any possibility. Rear o2 is in rear cat. (Rear cat is part of left front engine pipe.) Really do not want to guess on replacing left pipe Dana
February 07, 2008
2000 Oldsmobile Alero GX 2.4L Hesitation VIN: 1G3NK52T9Y
P0420: Catalyst System Low Efficiency. ... installed. avging 1 1/2 months between code reappearing(p0420). 2 time there were missfire codes with the cat code. all scan reading seem normal. we have reprogramed the ecm also. any help would be greatly appreciated
February 15, 2008
2001 Lincoln LS 3.0L Excessive Emissions, MIL Lamp on VIN: 1LNHM86S31
P0420: Catalyst System Effcieincy Below Threshold Bank 1. ... debacle, the subject car now threw a Check Engine light with a P0420 code (Bank 1 catalyst efficiency below threshold). Vehicle was driven between 100 and 200 miles in a misfire condition (running on 4 or 5 cylinders). Was curious if that is typically en...
February 16, 2008
1995 Jaguar XJR 4.0L MIL Lamp on VIN: SAJPX1149S
P0420: Poor cat efficiency A Bank. This car has stored the above codes. The P0116 seems straightforward enough, but the codes relating to EGR are a mystery as the car has no EGR valve. I ordered a new one to make sure that I wasn't missing something, but there are only air injection pipes comin...
February 20, 2008