I have The codes PO171 and PO174. The S-10 Blazer runs like a newSUV. I replaced the Fuel Injectors, gave it a complete tune up and replaced all the O2 Sensors. Light keeps coming and then going out every time I fill up with gas or gets below a half a tank. I replaced the fuel injection system two or three years ago. Computer says Map sensor is fine. Just can't keep the light from coming on. Light started coming after I had the transmission replaced
Please Help!

 

Here ya go

https://blazerforum.com/forum/diagno...plained-35154/

https://blazerforum.com/forum/diagno...plained-31560/

Read these over

 

So you are getting a code that is indicating that both banks of the engine are running lean. The combination of the two codes indicates a problem that is affecting both banks equally.

For some ideas, besides looking at the OBD2 diagnostic links above, you can look through what other people have experienced with these two codes by searching for "P0171+P0174". After reading up with what others have gone through, if you still have questions, please let us know.