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P0420 Diagnostic Trouble Code Discussion for July 2013

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2007 Chevrolet Equinox LT 3.4L MIL Lamp on VIN: 2CNDL73F67
P0420: Catalyst System Low Efficiency (Bank 1). ... tech's that have seen and done it all with this one. We are a used car dealer and busy repair shop. We sold this Equinox, and it has boomeranged 2x so far. The car runs good , scan tool on, good fuel trims, long & short , never misfires, rear O2 for th...
July 21, 2013
2001 Cadillac Seville STS 4.6L MIL Lamp on VIN: 1G6KY54991
P0420: Catalyst System Low Efficiency - Bank 1 (California). ... while monitoring O2 sensor data. Heard AIR pump turn on and saw Bnk1 Sensor1 O2 drop too 30 mV, other O2 sensors dropped to or around 0 mV. According to diagnostic chart system is working OK as long as B1S1 O2 drops below 350 mV I noticed that the system g...
July 26, 2013