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P0420 Diagnostic Trouble Code Discussion for December 2004

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1998 Honda Accord EX 2.3L Excessive Emissions VIN: 1HGCG5650W
P0420: Catalyst Efficiency Below Threshold (Bank 1). Hi everyone. This gal's cat failed shortly after she accidently put diesel fuel in her tank. I replaced it with a known-good factory cat and about a year later here it comes again with low cat efficiency. Owner's husband smelled sulphur/egg smell in the garag...
December 10, 2004
1999 Honda Civic EX 1.6L MIL Lamp on VIN: 1HGEJ6572W
P0420: Catalyst Efficiency Below Threshold (Bank 1). ... it stalled out while driving after lights went dim. Upon testing the charging system, previous tech said there was no output from the alternator. Installed a reman. alternator. System is now charging off idle, but the mil stays on. Codes P1298, P0135, and ...
December 21, 2004