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P0420 Diagnostic Trouble Code Discussion for June 2004

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1998 Ford Explorer XLT 5.0L MIL Lamp on VIN: 1FMZU35PWZ
P0420: catalytic convertor efficiency low in bank 2. code p0420 and p0430 keep coming on for catalytic convertor efficiency below limit in banks 1 and 2. initially, the vehicle came in with a p0300 code for random misfire, and we changed plugs and wires and removed fuel injectors for service. then we started to ...
June 15, 2004
2000 Saturn LS1 2.2L Misfire, MIL Lamp on VIN: 1G8JU52F2Y
P0420: Catalyst System Low Efficiency (Bank 1). ... world. This car will run OK for several days then start to miss once in a while and the check engine light will come on but not necessarily in that order. Plugs were original and worn so we replaced them with the proper ACDELCO plugs and flushed (MotorVac)...
June 22, 2004