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P0420 Diagnostic Trouble Code Discussion for December 2009

Catalyst Efficiency Below Normal (Bank 1)

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Trouble Ticket Help Requests for DTC P0420
Help Request Posted
2005 Nissan Frontier SE 4.0L MIL Lamp on VIN: 1N6AD07U85
P0420: Catalyst Efficiency Below Normal (Bank 1). New customer. Complaint of intermittent c.e.l, scanned & both b-1 & b-2 cat efficiency codes. Road test & runs fine. We mainly do domestic, and the test procedure seems pretty vaigue. Local dealer has cats in stock & are fairly expensive. To da...
December 02, 2009
2003 Saturn L200 2.2L Hesitation, Misfire, Poor Fuel Economy, MIL Lamp on VIN: 1G8JU54F73
P0420: Catalyst System Low Efficiency (Bank 1). I'm having a shifting issue with this vehicle, its lacking power too but that can be due to the cat converter(waiting for part). The unit shifts at high RPM under load 3900 to 4100 rpm. When at express way speeds under acceleration it will down shift to 2nd ge...
December 10, 2009
2000 Lexus ES300 3.0L MIL Lamp on VIN: JT8BF28G0Y
P0420: Catalyst Efficiency Below Normal (Bank 1). I have this '00 Lexus ES300, code P0420, looking at bank 1, it looks like the cat is seperate from the manifold, but the front cat (bank 2) is part of the manifold, I also see only one cat monitor sensor, do I need to replace the rear manifold to replace bank ...
December 14, 2009
2005 Chrysler Pacifica Limited 3.5L MIL Lamp on VIN: 2C4GF68485
P0420: Catalyst Efficiency Below Normal (Bank 1). I am checking the catalyst and O2 operation on this Pacifica. The O2 sensor readings on the scanner are 2.5 to 3.5 volts, fluctuates back and forth, desired is 2.7V. Why are they not the usual .2 - .9 Volts and fluctuating? Does Chrysler do something different...
December 22, 2009
2003 Jaguar X-Type 3.0L Poor Idle Quality, Cuts out, Misfire, MIL Lamp on VIN: SAJEA51C43
P0420: Catylist efficiency. Symptom of very rough idle and missfire during warm-up, MIL flashes upon attempting to accelerate while in park. After at least 50% warmed up engine starts to smooth out and MIL quits flashing. Cleared all codes but all return within a day or so. Engine runs w...
December 29, 2009
1997 BMW 740i 4.4L MIL Lamp on VIN: WBAGF832XW
P0420: Cat sys efficiency below threshold bank 2. ... and found lean codes for bank 1 and 2. No other codes. Smoke checked and found the intake rear cover and the pcv tube under the intake leaked badly. Removed manifold and replaced pcv tube, all gaskets and the rear cover.Smoke checked again-all ok. Cleared ...
December 30, 2009
2000 Mazda Protege ES 1.8L MIL Lamp on VIN: JM1BJ2228Y
P0420: Catalyst Efficiency Below Normal (Bank 1). Thanks for reading this. The problem is that my scanner (Genisys with system 3.0 and 2008 software and cable)shows LT fuel trim to be -77% to -71%, while ST fuel trim is anywhere from 250% to 22,000%! That is not a typo--22,000 percent fuel trim. Now, we all k...
December 30, 2009