Help! Trouble Code PO420?
Thread Starter
Staging Lane
Joined: Aug 2004
Posts: 61
Likes: 0
From: Humble,TX.
Help! Trouble Code PO420? Went to get my car inspected and just before getting there my car's SES light came on. The guy told me it was trouble code PO420 but he didn't know what side it was refering to (BANK 1). Does anyone know what it will take to repair this and what it might cost?
Thanks,
Pete
Thanks,
Pete
bank 1 refers to the left side. P0420 is Catalyst System Low Effeciency Bank 1. Either you have a bad 02 sensor(2nd 02 sensor on the drivers side(after the catalyctic converter) or you have a bad converter. I would try replacing the sensor and if the problem continues, you will need a converter...if your car is less than 8 yrs old and has less than 80,000 miles, the converter is still a factory warranty covered item. this will save you the 350-400 bucks it would cost to put a gm converter back on.
TECH Senior Member
Joined: Nov 2001
Posts: 7,036
Likes: 1
From: Lake Zurich, IL
As stated, driver side... you can try swapping rear O2 sensors around and see if the code follows... if it does then it's a bad O2 sensor, if it doesn't then it's likely a bad converter
As mentioned, they are warrantied for 8 years/80k (so long as they can't prove something on the car blew the cat out)
As mentioned, they are warrantied for 8 years/80k (so long as they can't prove something on the car blew the cat out)
Thread Starter
Staging Lane
Joined: Aug 2004
Posts: 61
Likes: 0
From: Humble,TX.
Car only has 24k miles on it so not sure if it's a bad cat. I did buy a new rear oxy sensor but have not yet installed it. Is this part easy to install? what do I need (tools)to install? Thanks for any info on this.
Originally Posted by ponchoWS6
Car only has 24k miles on it so not sure if it's a bad cat. I did buy a new rear oxy sensor but have not yet installed it. Is this part easy to install? what do I need (tools)to install? Thanks for any info on this.
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TECH Senior Member
Joined: Dec 2001
Posts: 5,399
Likes: 3
From: Jacksonville, FL
Yep, they can fail at any time - buddy had his replaced at less than 30K. The sensor is easy to change, just unhook the wiring harness - unscrew sensor - screw the new one in - reconnect harness. No special tools, drivers side rear is easy to get to, even a large crescent wrench will work.
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Verdad Gallardo $105! ouch! for future ref. there are some sites out there where you can get gm parts for half the price. Then again $105 is a lot better not having to chase a problem anymore
fwiw I had the same code p0430 (bank 2). Had the code cleared (thanx again Ed) and it hasn't returned in over 250miles / 30 or so start up cool down cycles (knock on wood). So I'de say just clearing the code is an option.
