Join Now
International Automotive Technicians Network

P0420 Diagnostic Trouble Code Discussion for July 2009

Catalyst Efficiency Below Normal (Bank 1)


Note: This is a professional automotive technician's resource.
Vehicle Owners: If you are seeking an automotive repair professional to service your vehicle, visit the iATN Repair Shop Finder.

Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2005 Nissan Frontier LE 4.0L MIL Lamp on VIN: 1N6AD07U85
P0420: Catalyst Efficiency Below Normal (Bank 1). Nissan Techs need some help. Truck was originally brought in at 44k with an internal engine problem that was caused by an aftermarket supercharger system. Engine was replaced with used unit and supercharger was removed.PCM had been modified for supercharger op...
July 01, 2009
2004 Nissan Sentra 1.8L Hesitation, Cuts out, MIL Lamp on VIN: 3N1CB51D05
P0420: Catalyst Efficiency Below Normal. new camshaft sensor and harness connector but fault still happens when cool.
July 08, 2009
2004 Nissan Sentra 1.8L Hesitation, Cuts out, MIL Lamp on VIN: 3N1CB51D05
P0420: Catalyst Efficiency Below Normal. new camshaft sensor and harness connector but fault still happens when cool.
July 09, 2009
2003 Chevrolet Malibu 3.1L Excessive Emissions, MIL Lamp on VIN: 1G1ND52J83
P0420: Catalyst System Bank 1 Low Efficiency. reoccuring 420 does any one else see this problem on gm mainly on 3.1 and 3.4 several cats have been installed even heavy metal cats always fails 420 no reflahs found for this car what is the fix?
July 13, 2009
2002 Cadillac DeVille 4.6L MIL Lamp on VIN: 1G6KD54Y42
P0420: Catalyst System Low Efficiency - Bank 1 (California). Hi everybody! Thanks in advance for your help. 3 months ago, this cadillac came in for lack of power and for check engine light. The code was for secondary air injection problem on bank 1. The car was tested, and yes, it lacked power. The air check valve was p...
July 16, 2009
1999 Mazda 626 ES 2.0L MIL Lamp on VIN: 1YVGF22CXX
P0420: Catalyst Efficiency Below Normal (Bank 1). Need help from the mazda gods! I have 99 mazda 626 2.0, its burned out 2 cats in the last 9 months, just cant figure out what to check. Everything looks ok to me, gets good gas milage. Please help.
July 20, 2009
1996 Chevrolet C1500 Cheyenne 5.7L MIL Lamp on VIN: 2GCEC19R1T
P0420: Catalyst System Low Efficiency (Bank 1). hi everyone. i have a problem here with this truck that will not communicate with my smog machine. it will communicate with the scanner very well, no problems there. i checked the grounds at the data link connecter and they all check ok. i do not knbow what i ...
July 22, 2009
1997 Ford Crown Victoria LX 4.6L No Start VIN: 2FALP74W4V
P0420: bank 1 cat efficienty below limit. will not start when owner goes away for a two week time we had the car for two weeks at our shop it failed good spark good fuel pressure check all imput sensors did the computer thump i kmow the mass air flow will set cat codes but will cause no start ater a l...
July 22, 2009
1996 Chevrolet K1500 5.7L Misfire VIN: 1GCEK14R8T
P0420: Catalyst System Low Efficiency (Bank 1). Good afternoon, I have what may be a stupid question but how do you go about verifing a bad injector assy on this Vortec? I have never had to replace one so I want to be sure it is bad. The truck has high misfire counts on cyl 3 and 5. Has some on cyl 6 but ju...
July 27, 2009