98 Chevy Truck check engine light came on...

...So I do a little research and find that I need a OBDII Code Reader to find out what's wrong. I go down to PEP Boys and buy one for $100. Very nice.

It tells me #P0135 - O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)

Now I'm wishing I had a manual. That'll be my next purchase.

I assume I need to replace the O2 Sensor. Can someone tell me where this O2 Sensor is located? Or any references to where I can get more information?

Thanks in advance!

DO NOT replace heated oxy sensor just yet. The code tells you that there's a malfunction in the "heater circuit". The testing procedure must be done (step by step) to pinpoint. Unless you want to spend $84 on a Heated oxy sensor, which probally wont cure problem.Do you want the test chart for P0135? I have it. It's 14 steps (maximum), you will need a Digital voltage multimeter.

Do you want the test chart for P0135? I have it. It's 14 steps (maximum), you will need a Digital voltage multimeter.
Yes, please post the test chart. That would be GREAT!
What manual does the test chart come from?
Thanks!

It's a suscription I have with Alldata. I will try to copy it , and save as jpg or a gif. last time I tried this for someone the file size exceeded the maximum allowed for posting images. I ended up sending it via personal e-mail. You can give me your e-mail address in private messages at this forum. Alldata is great, you get OEM service manual electronically, for $26 a year. Also all TSB's updated regularly.