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P0420 Diagnostic Trouble Code Discussion for February 2010

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2000 Honda Prelude 2.2L MIL Lamp on VIN: JHMBB6141Y
P0420: Catalyst Efficiency Below Threshold (Bank 1). ... quick testing it will go rich then return lean and stay below 10 millivolts. does not mimmic pre o2 at all. this car only sets a p0420 not a lean or low voltage code. could the new cat be too efficient? lol haven't had alot of time with this car yet but...
February 03, 2010
2001 Pontiac Bonneville SLE 3.8L MIL Lamp on VIN: 1G2HY54K81
P0420: Catalyst System Low Efficiency (Bank 1). Hello all, This Bonneville sets a P0420 converter code randomly. It typically happens at idle. It first came to me with an aftermarket converter that was very small. I connected my scanner and monitored fuel trims and watched the Upstream and downstream o2's. ...
February 03, 2010
2002 Oldsmobile Alero GL 3.4L MIL Lamp on VIN: 1G1NL52E32
P0420: Catalyst System Low Efficiency. catalytic converter has been replaced twice / there are no additional pcm codes present-o2 sensors are working correctly-is there a possible pcm update for this condition.
February 04, 2010
2004 Chevrolet Silverado 1500 5.3L MIL Lamp on VIN: 2GCEC19TX2
P0420: Catalyst System Low Efficiency (Bank 1). ... next day light on and code p0420 is on. I drove it for about 20 minutes and rechecked and found p0430 in code. this truck has a slight stumble at idle so I think it is the maf sensor. Back pressure test normal on cats did a crank test on the smog tester an...
February 10, 2010
1996 Toyota Tercel DX 1.5L MIL Lamp on VIN: JT2AC52L7T
P0420: Catalyst Efficiency Below Normal (Bank 1). ... into this before. I'll keep it short and sweet. Basically we have been getting this code for a while on this car. We first replaced cat at 90,000 miles. Same deal P0420. Replaced cat with OE toyota cat. Got same P0420 just over a year later. Toyota would n...
February 11, 2010
2004 Volkswagen Jetta GLS 2.0L MIL Lamp on VIN: 3VWSA69M54
P0420: cat system efficiency below threshold. Hello We have a vw jetta in our shop. Car came in with a broken front flex pipe witch is part of the cat. We changed the cat out with an aftermaket cat. The car came back in a few days later with the engine light on. The customer said the light goes on and of...
February 16, 2010
2007 Pontiac G6 2.4L Cuts out, Misfire, MIL Lamp on, spark knocking VIN: 1G2ZG58B17
P0420: Catalyst System Low Efficiency. customer came in because check engine light was on, scanned the pcm and found a misfire code and converter code. also complained that at highway speeds RPMs jump to 4 grand. only could get the car to act up doing 70 plus on highway. syptoms are hard accelerati...
February 22, 2010
1998 Honda Prelude 2.2L Hesitation, Stall VIN: JHMBB6242W
P0420: Catalyst Efficiency Below Threshold (Bank 1). ... lite pulled codes and found p0401 and p0420 customer opted to have cat repaired first came back two weeks latter for E G R valve. the valve was replaced pulled the plugs on intake manfolid and cleaned all egr ports all ports where cloged closed put it back...
February 24, 2010
1997 BMW 318i 1.9L MIL Lamp on VIN: WBACC9328V
P0420: Cat effeciency. ... and it had a P0420 stored I replacee the cat the down stream O2 sensor. When I was driving it the cam sensor went and I replaced that. It came back in with in October with the same code and the cat was ratting.(it is a Bozle cat) I put in another cat and i...
February 25, 2010