2001 kia sportage cel code p0171

:confused: My sportage is showing code p0171 again. When it first happened, I changed the front O2 sensor,the ignition modules, and got a fuel system treatment. Now the light has returned after 4 mths. Any suggestion on the problem?

Code P0171 Is "Exhaust too lean bank 1".

Is the engine running rough when first started ?

You did not mentioned the engine size.

Simple things to check would be vacuum lines, loose, cracked, not attached.

Intake gasket leak, spray some quick start around the gasket area and listen for a change in your idle. Be careful doing this, highly flammable.

Any areas that could be leaking vacuum that is un-known to the PCM i.e. any areas after the MAF sensor.

It's the 2.0 4 cyl. It doesn't idle rough, I thought it might be that the injectors needed replacing. I'll check for any vaccum to see if that's the problem.

If it is not a vacuum leak, another possibility is the fuel pressure, exhaust leak allowing pure air into the exhaust to the o2 sensor(s), fuel pressure regulator, or a bad MAF sensor.

Recommend getting a Chilton's or Hayne's manual, if you do not already have one, for troubleshooting purposes.