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P0420 Diagnostic Trouble Code Discussion for June 2012

Catalyst Efficiency Below Normal (Bank 1)


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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2006 Toyota Sienna LE 3.3L Misfire, MIL Lamp on VIN: 5TDZA23C46
P0420: Catalyst Efficiency Below Normal (Bank 1). ... Vehicle came in with a light misfire. Also had multiple codes stored. Cleared codes and P0305 comes back immidiately. Misfire data shows a constant misfire count. Performed a tune up due to original plugs. Swapped coil to #6 hole, to see if miss changed cy...
June 01, 2012
2003 Jeep Wrangler Rubicon 4.0L Excessive Emissions, Poor Idle Quality, Hesitation, Cuts out, Stall, Misfire, Poor Fuel Economy, MIL Lamp on, Hard start & stall VIN: 1J4FA69S23
P0420: Catalytic Converter Efficiency (Bank 1). This is my personal play toy. I use it for offroad so it is modified, but no mods that I feel would trace back to this issue. That is always my first on the check list, to rule out any problems related to the last modification. The jeep will start run for a f...
June 03, 2012
2006 Toyota Sienna LE 3.3L Misfire, MIL Lamp on VIN: 5TDZA23C46
P0420: Catalyst Efficiency Below Normal (Bank 1). ... Vehicle came in with a light misfire. Also had multiple codes stored. Cleared codes and P0305 comes back immidiately. Misfire data shows a constant misfire count. Performed a tune up due to original plugs. Swapped coil to #6 hole, to see if miss changed cy...
June 07, 2012
2003 Nissan Frontier XE 3.3L Hesitation VIN: 1NGED29Y13
P0420: Catalyst Efficiency Below Normal (Bank 1). vehicle came in with complaint of low power and stumble. have these codes. removed right side converter and inspected, manifold for clogged converter, looks ok, right side is bank one on this engine right? also i'd seen prior posts about if the bank has 100% f...
June 13, 2012
2002 Hyundai Elantra GLS 2.0L Excessive Emissions, Poor Fuel Economy VIN: KMHDN45D12
P0420: Catalyst Efficiency Below Normal (Bank 1). This vehicle is giving a reading on o2 sensors when the engine is off (not running) we have trried a good known computer and the problem is still the same. Both o2 sensors are reading the same 420 and 424 . I did read another post who had the similar problems ...
June 20, 2012