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P0421 Diagnostic Trouble Code Discussion for April 2007

Warmup Catalyst Efficiency Low (Bank 1)

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Trouble Ticket Help Requests for DTC P0421
Help Request Posted
2000 Saturn LS2 3.0L MIL Lamp on VIN: 1G8JW52R6Y
P0421: warm up catalyst below threshold. this customer called me and asked for a tow into the shop from a nearby town because the car stalled and then would crank and not start but she wound up being able to start car after waiting one half hour.car started up for us but on road test it would stall a...
April 20, 2007