Question about 2002 Chevrolet Express

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Engine code p0420 on 2002 Chevrolet Express Van V8

Engine light came on checked problem and got code P0420 with the message, Catalyst Efficiency Below Threshold (Bank 1). The only symptoms are running a little rough at idle and seems to be using a lot of gas (a little over 10mi/gallon). It's the larger V8. We are thinking it's the rear 02 sensor but any information you could offer would be appreciated. Thank you!!!

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Hello!

the code you speak of relates strictly to the catalytic converter. it is possible there is a faulty sensor, however that choice is highly unlikely. Catalytic converters carry a 5/50 7/70 and 8/80 warranty depending upoin the state you live in...this may be a repair covered under manufacturers warranty. this code is becoming very prevelant in many auto lines as a result of the insurgence of ethanol dilution of our fuels. the "10%" ethanol sticker is located on most pumps. Most vehicles on the road today are not flex fuel capable and this ethanol is wreaking havoc on our fuel and emission systems, especially the catalytic converters. the converters are caked with deposits from the ethanol, reducing its effeciency. if your have access to well worth branded products (not available in ANY parts store, typicaly dealers and repair shops only) try adding on succesive tank loads of fuel their product called Octi-Plus. this products helps remove ethanol products, and very well may save yoiu big $$$ for that converter repair bill...i hope this helps..check out this link....

http://www.wellworthproducts.com/

ps i appreciate your 4 thumbs up if this helps you!

Posted on Jun 19, 2009

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Posted on Jan 02, 2017

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