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P0420 Diagnostic Trouble Code Discussion for August 2011

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2005 Chevrolet Aveo LS 1.6L Hesitation, Cuts out, MIL Lamp on VIN: KL1TD626X5
P0420: Catalyst System Low Efficiency. Hello out there to all you chevy aveo technicans out there) igot this chevy aveo that wil hesitate severely, back pop through the intake(and falls onits face) it only does it every once and awhile) feels like no fuel pressure. But fuel pressue is steady at 65 ...
August 04, 2011
2006 Chrysler Pacifica Touring 3.5L MIL Lamp on
P0420: Catalyst Efficiency Below Normal (Bank 1). I have the car I have tried everything. I dont want to just throw parts at it. I cant find definition for 2 codes but I feel this is a wiring problem i have checked and wiggled all the wiring i can get to but i cant figure it out. the car runs fine but the eng...
August 04, 2011
1999 Land Rover Range Rover 4.0L Misfire, MIL Lamp on VIN: SALPA1247X
P0420: Cat below efficiency bank 1. First time customer came in stating check engine light and run rough. Scan for code and foung the listed codes in system. Engine have misfire while idling. Inspect spark plug wires and found arcing on spark plug. Can't seem to figure out which cylinder is miss...
August 16, 2011
2006 Chevrolet Express 3500 4.8L Misfire VIN: 1GCHG39V96
P0420: Catalyst System Low Efficiency (Bank 1). Hello and thank you for your time and help. This van runs okay cold and hot. Once it has been hot for maybe 20 minutes of continous running it will start missing either driving or idling. No. 1 cylinder is most noteable. Swapped coils, plugs, and a plug wire. ...
August 24, 2011
2006 Toyota Sienna Limited 3.3L MIL Lamp on VIN: 5TDBA22C26
P0420: Catalyst Efficiency Below Normal (Bank 1). ... runs fine, scanned got codes p0420 and p0430. Did a smoke test to check for vacuum leaks and it passed. A/f readings ok. I was wondering if anyone has had cat problems on these newer vans? If so which ones it has three? A...
August 25, 2011
2005 Dodge Grand Caravan SXT 3.8L MIL Lamp on VIN: 2D4GP44L45
P0420: Catalyst Efficiency Below Normal (Bank 1). ... changed the spark plugs and set the code p0420
August 26, 2011
2005 Jeep Grand Cherokee Laredo 3.7L long crank time VIN: 1J4GR48K15
P0420: Catalyst Efficiency Below Normal (Bank 1). Well maintained Jeep and a regular customer.Heads were pulled and a complete valve job done due to a misfire caused by carbon buildup.Since then it has developed a hard start when hot.Cold it will fire right up,run to temp shut it down ,let it sit 15-20 minute...
August 29, 2011