P0420 and gas issue??

[edennis]

So around the same time my check engine light came on and I also started thinking I was running through gas way to quickly. I haven't had time to actually check my current mileage, but I got the check engine light checked and its a P0420 Catalytic code.

The car is a 04' fwd manual base. Are these two symptoms connected? I am not noticing any loss of power- but for now I had the light turned off and I will see what happened. What should I be thinking about here/what can I do to narrow down the issue?

Thanks in advance,

Eric

[joatmon]

It is possible that a partially clogged cat converter could drop mpgs, and a bat cat will cause a P0420.

Might not be a bad cat, but it could be

[jolt]

Here are two places to get some idea of what to be looking at:

http://ricksfreeautorepairadvice.com/ho ... ode-p0420/

http://www.autocodes.com/p0420_toyota.html ;and check the some of the links at the bottom of this page too.

[edennis]

Thanks for the links, that's great. I'm hoping it's something along the lines of an 02 sensor and not a bad cat. It does have 190k on it though and to my knowledge never had the cat replaced- so, maybe it time? We'll see.

[jolt]

Here is another link with more direct info. The title is "Understanding and diagnosing Toyota P0420 DTC".

http://www.autoserviceprofessional.com/ ... DTC?Page=1

An exhaust leak that pulls air into the exhaust in front of the OS can trick the computer into thinking that the engine is running lean and cause it to use more fuel. A bad MAF sensor can cause rich fuel mixture too and that will make the fuel mileage drop. If you follow the above article, in the order that they suggest, you should find the problem or problems. A bad convertor is the result of something else being bad. Be sure to check your fuel trim.