P0170 reading on a toyota tercel

That code stands for "fuel trim malfunction", and is usually accompanied by another code indicating rich or lean. Do you have anything else?

I got the similar problem with my Toyota Corolla 2000, and it says Lean. The dealer diagnosed dirty fuel injector and asking $600 for repair. From some reading that I have done, 5 years is too early to have to replace / clean the injectors. Any thoughts?

An injector shouldn't foul in 5 years unless you often use cheap gas or gas from a station that does not sell high volume.

You might try Chevron Techron fuel injector cleaner, available at auto parts stores and Chevron stations to see if the problem clears up. The fuel injector cleaner that Toyota dealer parts departments sell also works well.

No that is the only code I get I know that its the fuel trim malfunction, but I would like to know the location of the problem does anyone know where it would be?

Without any other symptoms or codes the only way you'll be able to pinpoint anything is by looking at the datalist to see various sensor inputs or looking at stored freezeframe data to see sensor conditions when the fault occured. That code by itself covers too broad an area to fix without diagnosis. I would suggest finding a technician.