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P0420 Diagnostic Trouble Code Discussion for August 2008

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2002 Nissan Pathfinder SE 3.5L MIL Lamp on VIN: JN8DR09Y62
P0420: Catalyst Efficiency Below Normal (Bank 1). Came in for continuous p0420 and 430 . both bank cat inefficiencies. Both downstram o2s were changing as fast as front o2s, replaced both cat converter assys, and keep getting code 420, the 430 is gone, then replaced 1 o2 at a time , until all 4 replaced , sam...
August 20, 2008
2003 Toyota Tacoma S-Runner 3.4L MIL Lamp on VIN: 5TEWN72N23
P0420: Catalyst Efficiency Below Normal (Bank 1). ... replaced the Bank 1 sensor 2 with a Bosch O2 sensor. The vehicle then passed inspection. 6 weeks later the vehicle exhibited a P0420 code. I replaced both sensor 1 and sensor 2 (2nd time) with Bosch parts which did not fix the problem. I then replaced both...
August 31, 2008