The dreaded P0420 code....

[the 18th letter]

Went and got my SES light read and up popped p0420.. Def: catalyst efficiency low bank 1. Explanation : the oxygen sensors monitor catalytic converters ability ot store oxygen. Probable cause: CC defective due to engine misfire or running condition; large vaccum leak; or engine oil leakage into exhaust valve guide, seals, and/or piston rings. How does a DIY'er go about chasing this down. Fraudozone wouldn't clear the code for me either... Any suggestions appreciated

 

[SunlitComet]

replace your converter assembly. that is both and if you have not done int in the last 40,000 miles replace all the O2 sensors along with it.

 

[jd123]

Us Autozone employees don't clear codes because it's illegal and we could lose our jobs over it at the least if anyone found out.

 

[sumo]

Us Autozone employees don't clear codes because it's illegal and we could lose our jobs over it at the least if anyone found out.

clearing codes is not illegal. Maybe its in your company's policy. But not Illegal. Changing batteries/unhooking them will also reset CEL but my local autozone changes batteries all the time for customers. Cats are not cheap. You can clear the code and depending how bad the cat is, it can stay off and might not come back, or if its really bad, it will come back right away. Ive cleared that code on customers cars before that declined to replace the cat and seen them again months later without them complaining of a CEL or 0420 code

 

[bowtiefreak]

codes like that are emmsions related and some states may have rules like that....not sure though.

Quick emmisions example from the lovely EPA: (totaly off subject but I'm telling it anyway)

I bought a husky chain saw and leaf blower. Well, the saw stopping working correctly, stalling on the top end and under load. Me knowing what to do went to adjust the high speed mixture....guess what, a special tool is required to do that. Why you may ask? Because they are factory set and the EPA was behind that so that a consumer can not adjust that saw possibly creating more polution. Anyone found selling the special tooling required would receive a fine if not more. I now have a tool though but the point of my story is that vehicle emmisions is touchy business, ask anyone in CA

 

[the 18th letter]

Autozone has cleared a CEL light for me in the past, which is why I called them fraudozone, for not doing it this time! LOL. I def wouldn't want to see anyone lose their job, no biggie.

I passed emissions here in October the first time through, so no problems recently. Last time I changed an O2 was more than 40k ago, about 55k ago.

Ok, stupid question, but disconnecting the battery won't affect my BB tune will it? The computer should just reset to a 'restore' point within the BB tune right?

Also, gas mileage has been crappy for the past couple of months. I attributed it to putting on the 22's in the spring but seems drastic from 15 miles to about 11-12 miles a gallon...

 

[sumo]

no it wont. The Tune from BB is Flashed/overwrites into your ecm so there is no alternate setting.

 

[SunlitComet]

the tune is stored in the ROM not RAM.

 

[the 18th letter]

Cleared the code and drove all week without it coming back on. Hope it can hang on until income tax returns when I can afford a repair. Thanks for the help fellas....

 

[yukonaetahoe]

Anyone reccomend a specific code scanner? Looking to buy one....