Diagnosing A P0420 Code On Silverado 1500

[Digger02]

Hi,

 

I've got the dreaded P0420, Low Efficiency in Catalytic Bank One code on a 2003 Silverado 1500 5.3 V8 at about a 142,000 miles. If I reset the code, it comes back after about 100 miles of driving.

 

I changed the Cat at about 75,000 miles with a non-OEM unit, but still the Y-pipe with 2 cats. I'm far poorer now than I was in 2006, so I'd like to "try" cheaper fixes than just replacing the cats (although the Eastern units are down to less than $350 with shipping).

 

Where do I start - what does "bank 1" indicate? Is it worth removing O2 sensors and cleaning them? How do I know O2 sensors are good? Is swapping O2 sensors around worth it? Are all "catalytic convert cleaner additives" the same as "snake oil"?

 

If I go with the Eastern replacement unit, how hard is it to remove bolts/clamps? The cat was changed once, so maybe about 4.5 years since last replacement. Are there gaskets to replace?

 

Any suggestions ?

 

Thanks

 

Dave

[txab]

Bank one is the drivers side head, the head head with the #1 cylinder. Bank 2 is the head with #2 cylinder.

 

so your driver's side cat may be having trouble or the sensor may be having trouble, especially if is original.

 

I know one of my vehicles my problem cleared itself after switching fueling stations. Whenever anyone drove it they always put wal-mart gas in it. Once I no longer allowed that, the problem cleared. Try to stay with Top Tier fuels.