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P0420 Diagnostic Trouble Code Discussion for December 2013

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1999 Dodge Dakota 3.9L MIL Lamp on VIN: 1B7FL26X5X
P0420: Catalyst Efficiency Below Normal (Bank 1). ... replaced twice due to a P0420 code that resets after about 3000mi. Upstream and downstream sensors are switching at same rate. Upstream sensor does not seem "lazy". Both sensors react to richening/leaning system. They do not look OE, but we have no...
December 03, 2013
2002 Cadillac Seville SLS 4.6L MIL Lamp on VIN: 1G6KS54Y92
P0420: Catalyst System Low Efficiency - Bank 1 (California). ... misfires. Found bad ign module. Replaced and ran good. Came back a month later with p0420 code. Cat effic. Replaced the cat with bolt on eastman cat. 2 months later same code. Replaced again. Just under 2 months, same code came back. Replace again. 2 weeks...
December 11, 2013
2008 Chevrolet Avalanche LS 5.3L MIL Lamp on VIN: 3GNFK123X8
P0420: Cat inefficency. ... I have 13 codes the main codes are listed above but it also had some rich codes the other converter code a brake light switch performance code and misfire codes . This truck is pretty beat and the lifters are ticking. Now heres what Ive done . It was towed...
December 19, 2013
2008 Toyota Tundra SR5 5.7L MIL Lamp on VIN: 5TFBV54158
P0420: catalyst system efficiency below threshold bank 1. Vehicle came in for code (p0420) set for catalyst system efficiency below threshold b1. Monitor with scanner and found both oxygen sensor jump identical, both rear oxygen sensor also jump identical too. I cleared the check engine light. Test drive for readines...
December 26, 2013
2005 Hyundai Santa Fe 2.7L MIL Lamp on
P0420: Catalyst Efficiency Below Normal (Bank 1). trk brought to shop w/mil lite on and a concern for a 1800 rpm idle @ cold start up. coolant temp sensor code present. check @ coolant sensor plug for 5v reference signal, ok. pulled t/stat off to check for being stuck open,ok. did back pressure test on both c...
December 31, 2013