Join Now
International Automotive Technicians Network

P0420 Diagnostic Trouble Code Discussion for May 2006

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
2000 Nissan Maxima GLE 3.0L cat. monitor VIN: JN1CA31D3Y
P0420: Catalyst Efficiency Below Normal (Bank 1). This car came in last week with code p0420 stored and a rejection sticker on windshield for an emissions fault being stored, after checking found that an ecm reprogram is needed and maybe a cat. Took car to local dealer, a reprogram was done only, they said th...
May 11, 2006
2001 Chevrolet Express 1500 4.3L No Start, Poor Idle Quality, Hesitation, Cuts out, Stall, Misfire, MIL Lamp on VIN: 1GCEG15W01
P0420: Catalyst System Low Efficiency (Bank 1). well then, got one that likes my shop. came in running horrible. on test drive massive misfire around 1/4-1/2 throttle especially and began stalling on the way back. got it into shop cut it off hasnt started since. tune up was done last october full set of ev...
May 19, 2006
2001 Toyota Corolla CE 1.8L Excessive Emissions VIN: 1NXBR12EX1
P0420: Catalyst Efficiency Below Normal (Bank 1). ... a headache...has a code p0420 cat converter bk 1 operating below threshold.. replaced upstream 02 due to not very responsive,noe it looks good while driving,switching normally.came back same code..i then figured it was possibly the cat replaced it test dri...
May 19, 2006
1999 BMW 318ti 1.9L MIL Lamp on VIN: WBACG7331X
P0420: Catalytic converter efficiency below threshold. ... the old run-around. It has had a P0420 for catalytic conversion below snuff for a while and the customer decided to go for the repair as it needs an emissions test. I checked for other codes none found and ordered an aftermarket bolt in cat. Unit fitted ...
May 22, 2006
1999 Mercury Cougar 2.5L monitors won't run VIN: 1ZWFT61L6X
P0420: cat efficency low bank 1. Hello fellow iATN members, I have this cougar that failed inspection for PO420. Had computer flashed per TSB. Drove vehicle for several days and cannot get evap and catalyst monitors to run, including a long highway run at steady 60MPH, let sit overnight, road...
May 22, 2006
2000 Subaru Forester 2.5L MIL Lamp on VIN: JF1SF6551Y
P0420: Catalyst Efficiency Below Normal (Bank 1). ... Subaru that has been kicking my back side for about 7 months now and could really use some outside advise on it. The problem is the ECM continues to set code P0420. It is on it's 3rd set of cat's (counting the original set)and it's 3rd oxygen sensor (count...
May 22, 2006
2001 Chevrolet Express 1500 4.3L No Start, Poor Idle Quality, Hesitation, Cuts out, Stall, Misfire, MIL Lamp on VIN: 1GCEG15W01
P0420: Catalyst System Low Efficiency (Bank 1). well then, got one that likes my shop. came in running horrible. on test drive massive misfire around 1/4-1/2 throttle especially and began stalling on the way back. got it into shop cut it off hasnt started since. tune up was done last october full set of ev...
May 24, 2006
2000 Ford Contour LX 2.0L MIL Lamp on VIN: 1FAFP6636X
P0420: Catalistyc Eficience low bank 1. ... on and I read the trouble code p0420, and I checked the converter catalistyc and the o2 sensor but didnt find anything, I need your help.
May 29, 2006
2000 Nissan Maxima GLE 3.0L cat. monitor VIN: JN1CA31D3Y
P0420: Catalyst Efficiency Below Normal (Bank 1). This car came in last week with code p0420 stored and a rejection sticker on windshield for an emissions fault being stored, after checking found that an ecm reprogram is needed and maybe a cat. Took car to local dealer, a reprogram was done only, they said th...
May 11, 2006
2001 Chevrolet Express 1500 4.3L No Start, Poor Idle Quality, Hesitation, Cuts out, Stall, Misfire, MIL Lamp on VIN: 1GCEG15W01
P0420: Catalyst System Low Efficiency (Bank 1). well then, got one that likes my shop. came in running horrible. on test drive massive misfire around 1/4-1/2 throttle especially and began stalling on the way back. got it into shop cut it off hasnt started since. tune up was done last october full set of ev...
May 19, 2006
2001 Toyota Corolla CE 1.8L Excessive Emissions VIN: 1NXBR12EX1
P0420: Catalyst Efficiency Below Normal (Bank 1). ... a headache...has a code p0420 cat converter bk 1 operating below threshold.. replaced upstream 02 due to not very responsive,noe it looks good while driving,switching normally.came back same code..i then figured it was possibly the cat replaced it test dri...
May 19, 2006
1999 BMW 318ti 1.9L MIL Lamp on VIN: WBACG7331X
P0420: Catalytic converter efficiency below threshold. ... the old run-around. It has had a P0420 for catalytic conversion below snuff for a while and the customer decided to go for the repair as it needs an emissions test. I checked for other codes none found and ordered an aftermarket bolt in cat. Unit fitted ...
May 22, 2006
1999 Mercury Cougar 2.5L monitors won't run VIN: 1ZWFT61L6X
P0420: cat efficency low bank 1. Hello fellow iATN members, I have this cougar that failed inspection for PO420. Had computer flashed per TSB. Drove vehicle for several days and cannot get evap and catalyst monitors to run, including a long highway run at steady 60MPH, let sit overnight, road...
May 22, 2006
2000 Subaru Forester 2.5L MIL Lamp on VIN: JF1SF6551Y
P0420: Catalyst Efficiency Below Normal (Bank 1). ... Subaru that has been kicking my back side for about 7 months now and could really use some outside advise on it. The problem is the ECM continues to set code P0420. It is on it's 3rd set of cat's (counting the original set)and it's 3rd oxygen sensor (count...
May 22, 2006
2001 Chevrolet Express 1500 4.3L No Start, Poor Idle Quality, Hesitation, Cuts out, Stall, Misfire, MIL Lamp on VIN: 1GCEG15W01
P0420: Catalyst System Low Efficiency (Bank 1). well then, got one that likes my shop. came in running horrible. on test drive massive misfire around 1/4-1/2 throttle especially and began stalling on the way back. got it into shop cut it off hasnt started since. tune up was done last october full set of ev...
May 24, 2006
2000 Ford Contour LX 2.0L MIL Lamp on VIN: 1FAFP6636X
P0420: Catalistyc Eficience low bank 1. ... on and I read the trouble code p0420, and I checked the converter catalistyc and the o2 sensor but didnt find anything, I need your help.
May 29, 2006