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P0420 Diagnostic Trouble Code Discussion for August 2012

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2004 Chevrolet Trailblazer LS 4.2L Surge VIN: 1GNDS13S74
P0420: Catalyst System Low Efficiency (Bank 1). this vehicle has a slight surge at all times except at idle. the surge is about 50 rpms. it has a bad catalyst convertor. the rear 02 is switching with the front one. the surge seems to follow fuel trim & o2 sensor numbers. i unpluged rear 02 sensor & ...
August 14, 2012
2003 Dodge Neon SXT 2.0L Stall VIN: 1B3ES56C83
P0420: Catalyst Efficiency Below Normal (Bank 1). This car has been in every shop in town. It is a rebuilt wreck. It stalls intermittantly after first starting. About the time you pull out of the driveway and start to take off. It has had a used computer installed, new O2 sensor, new CMP sensor, transmission ...
August 30, 2012