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P0420 Diagnostic Trouble Code Discussion for June 2008

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1996 Chevrolet Blazer 4.3L Poor Idle Quality, Poor Fuel Economy VIN: 1GNDT13W8T
P0420: Catalyst System Low Efficiency (Bank 1). Hi guys, This vehicle has developed a rough running on start up that last for several miles. Rough enough the owner at times has to pull over and shut the engine off and restart it. Sometimes that helps. They say that the milage has gone way down. I know tha...
June 04, 2008
1996 Ford Crown Victoria LX 4.6L Misfire VIN: 2FALP74W9T
P0420: Bank 2 converter efficiency below limit. hello ford techs- we got a crown vic. that seems to miss under slight load- idle and full throttle ok, found EGR vavle coming on to soon- replaced EGR solenoid--still seems to miss Ignition pattern looks ok- but low amped coils to have patterns at times goes b...
June 05, 2008
1996 Ford F-150 Eddie Bauer 4.9L No Start, Cuts out, Stall, MIL Lamp on VIN: 1FTEF15Y4T
P0420: cataylist inefficency. this truck has a intermittent stall then a no start problem. customer brought it in a few months ago and i drove it home a few nights with no problems. i wanted to try something, so with another tech's input i replaced eec & fuel pump relay, i wanted to (a...
June 11, 2008
1998 Honda Accord EX 3.0L MIL Lamp on VIN: 1HGCG1658W
P0420: Catalyst Efficiency Below Threshold (Bank 1). Car has just had an aftermarket cat installed and the light came back after 8 days. Has anyone seen anything else cause this on an Accaord before I bite the bullet and buy a dealer cat? Just don't want any comebacks... Thanks in advance Brian
June 11, 2008
2000 Dodge Neon High Line 2.0L MIL Lamp on VIN: 1B3E546C5Y
P0420: Catalyst Efficiency Below Normal (Bank 1). ... cylinders had been washed out so a used engine had been istalled by us.road test was good. car came back, p0420 catalyst efficiency failure. replaced cat with factory cat.replaced both oxygen sensors. same code came back, note: the down stream oxygen senso...
June 13, 2008
1997 Mazda 626 DX 2.0L Excessive Emissions, MIL Lamp on VIN: 1YVGE22C3V
P0420: Catalyst Efficiency Below Normal (Bank 1). the car failed smog hc@ 15 and 25 mph, knox @15 mph ineed to run a couple of tests to prove or not of bad cat.
June 23, 2008
1999 Honda Civic EX 1.6L MIL Lamp on VIN: 2HGEJ8643X
P0420: Catalyst Efficiency Below Threshold (Bank 1). car came in with no check engine light or trouble code but customer saying it starts a little hard start, it was 30,000 mile since it had a tune-up. so we did a tune-up, customer pick up car and drove it home and called the next day with check engine light on,...
June 24, 2008
1999 Toyota Camry CE 2.2L MIL Lamp on VIN: 4T1BG22K1X
P0420: Catalyst Efficiency Below Normal (Bank 1). ... think I'm going to give the owner a key first time in was multipal codes P0171 lean bank 1,P0420 cat low efficience,P0446 Vacuum switching valve, P1130 B1S1 performance malfunction, P1133 circut responce malfunction, I replaced the AF sensor and the VSV va...
June 24, 2008
2002 Volkswagen Jetta GLS 2.0L No Start, Poor Idle Quality, MIL Lamp on VIN: 3VWSB69M22
P0420: CAT Efficiency below Threshold. I am not very familiar with the VW. My diagnostic scanner software is not the best for this either. I was able to retrieve the listed codes as well as some data stream. I did verify the ECT problem, it will intermittantly show -40 degrees F. and then return to...
June 26, 2008
1999 Mercury Cougar 2.5L MIL Lamp on VIN: 1ZWFT61L1X
P0420: cat efficiency. Hi guys I have a problem I never ran into and I'm hoping someone has. This vehicle has both bank 1 and bank 2 cat efficiency codes (po420&430). The post cat o2's are switching fast like a bad cat. My problem is there is a tsb for a reflash. So my question ...
June 30, 2008
2001 Volkswagen Golf GL 2.0L MIL Lamp on
P0420: catalyst effiency below threshold. wman came in with po420 testd o2 cat and fuel trim. could not get readings with mentor in generic or obd. replaced o2. both that is the readings were front .85 rear .32. they were 0 before. took it for a ride found exhaust was loud at acceleration found cat ha...
June 30, 2008