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P0420 Diagnostic Trouble Code Discussion for October 2007

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
1998 Lexus ES300 3.0L MIL Lamp on VIN: JT8BF28G6W
P0420: Catalyst Efficiency Below Normal (Bank 1). ... banger here, we replaced the catalyst and o2 on this vehicle over 1 year ago and all was well. Recently, however, the p0420 is back, retested vehicle, and keep coming up with a bad cat. We repalced it again, twice! Even slid in another o2 for good measure....
October 03, 2007
2001 Toyota Tundra 3.4L continuous code VIN: 5TBJN32198
P0420: Catalyst Efficiency Below Normal (Bank 1). Anyone ever run into continuous 420 code after replacing all required parts?
October 04, 2007
2000 Acura Integra LS 1.8L Excessive Emissions, Misfire, MIL Lamp on VIN: JH4DC4345Y
P0420: Catalyst Efficiency Below Threshold (Bank 1). ... hardly to delete, succeded to delete only when unplug the battery. Code P0420 always present. The rear O2 sensor it's stuck with 0.08 volts when idle, at 2500 RPM goes at around 0.5 volts. Front O2 works well. LTFT = 0.99 STFT = around 0.99 things done: Cl...
October 08, 2007
2000 Honda Civic Si 1.6L Surge, Cuts out VIN: 1HGEM1151Y
P0420: Catalyst Efficiency Below Threshold (Bank 1). during high engine rpm 5k to 8k, without cat or (burned out)this engine spools up to 8k without hesitation. no surge no resistance to accelerate. when new cat is installed (factory honda) the engine lacks power and surges when trying to accelerate past 5k rpm....
October 14, 2007
2003 Dodge Ram 1500 SLT 5.9L MIL Lamp on VIN: 1D7HU18DX3
P0420: cat eff. only problem is engine light comes back on after a few miles have replaced the cat and the front o2 sensor all started when replacement engine (used ) customer says light was never on before
October 17, 2007
2000 Mercury Cougar 2.5L MIL Lamp on VIN: 1ZWHT61L7Y
P0420: Loss of catalyst efficiency Bank one. We are ready to replace the cat when we raised the car up and got a surprise. There is no O2 sensor after the main converter, only after the pre-cats that are part of the exhaust manifold!! So, now, do we replace the pre-cat for bank one or the main converter ...
October 18, 2007
2001 Toyota Highlander 2.4L MIL Lamp on VIN: JTEGD21A51
P0420: Catalyst Efficiency Below Normal (Bank 1). Dealer has campaign to reflash but will not do so unless they diagnose and do repair. I am looking for a local (Orange County California Area) repair shop or member that has the equipment to do the reflash. I also talked to 1 800 GO TOYOTA and they said the d...
October 25, 2007
1999 Toyota 4Runner SR5 3.4L MIL Lamp on VIN: JT3HN86R5X
P0420: Catalyst Efficiency Below Normal (Bank 1). Keeps setting P0420, replaced air/fuel ratio sensor and it outputs a voltage of 3.2 volts @ idle all the way to the computer. The scanners (Modus) and (Mastertech) show 660mv for bank 1 sensor 1 (the air/fuel ratio sensor) and a varying 100mv to 900mv for the ...
October 26, 2007