lexway07

Hello all

I am a newbie, have a 99 es300 with 135k miles on it. My engine+trac light came on 3 weeks ago and it went off within couple days . It resurfaced again a week ago and went off within a day. Now since last few days it came back on and i took it to Autozone to get the codes. It was P1135 , P0171 and P0172 all together.The Autozone guy printed out the description of all the above errors. My Gas cap is tight.Checked the air Filter and its not that bad. I do notice the car as if its having breathing problem when i slow down to make a stop.It doesnt die or anything like that. Also my mileage is slightly low after this.

About 9 months ago i replaced 3 coils for misfires and replaced all the spark plugs. A local mechanic suspects the GAS fuel filter could be causing it as it hasn't been changed since last 2 years(20k miles).

Can some one please tell me what could be wrong here.If its a Mass air flow sensor or if its O2 sensor is the problem. I hate to buy both if its not required.
Should i have it scanned by a professional with a computer for more indepth diagnostic report to pin point the failed component? (they charge 50$) .
Also can someone please tell me where these are located (o2 sensors on bank1 sensor 1 or MAF) on the car if i can do it myself and what tools do i need.(to replace o2 sensor or MAF sensor).
If i have to clean the MAF sensor can i do it myself and what do i need to clean it.
Where can i buy these generic parts if anyone can reccomend to put on them ?
Also if its o2 sensor which o2 sensor should i buy , is it pre cat post cat , front or rear (i am confused)

Appreciate all your help in this matter.
aj

lexway07

Can somoene please help me ? should i replace o2 sensor or MAF ? ..and where they located at. how many are there for this es3000 1999 model..could bad fuel filter cause this?

appreciate it

dallison

it could possibly be the charcoal canister

lexway07

Thanks for the reply, Can you please tell me where is that located and how can i replace it?