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P0420 Diagnostic Trouble Code Discussion for May 2004

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1998 Ford Contour GL 2.5L Poor Idle Quality, Cuts out, Stall, MIL Lamp on VIN: 1FALP65L8W
P0420: Cat efficiency bank one. ... car, she has had some trouble getting it to "stay fixed" her local ford dealer replaced "some sensor" at least twice in the past year. I think she should have been covered under the 5/50 Emissions warranty then but they don't seem to be int...
May 03, 2004
1996 Jaguar XJ6 4.0L Excessive Emissions, black smoke VIN: SAJKX1745S
P0420: Catalyst Efficiency. Customer's complaint: black smoke going uphill...someone behind her even flagger her down to tell her it was smoking...I verfied only in shop (couldn't see anything on test drive) by quick thottle jabs and black smoke momentarily out of rear tailpipes. Ok...l...
May 08, 2004
1996 Ford Explorer Eddie Bauer 4.0L Excessive Emissions, Poor Idle Quality, Surge, Stall VIN: 1FMCU34X3T
P0420: CAT Efficiency below threshold Bank 1. Hello All, I have this Explorer that has me baffled. When it came in the shop I had several codes but found a main vacuum hose off so erased codes and only one has returned since and that was a PO171. However, that code did not return for several days in which...
May 31, 2004