Po171 system too lean bank 1 this code came up..the light on the dash is yellow and comes on then goes off. I put fuel injector cleaner in it just in case..but what does this mean??

code p 0171 refers to system too lean bank 1===causes --intake/exhaust leak---AIR system---MAF/VAF sensor---fuel pressure/ pump/ pressure regulator---injector/s---heated oxygen sensor (HO2S unit in the exhaust manifold or before the cat converter
If the engine is running well then consider replacing the HO2S unit as that reports to the ECM that then adjusts the mixture for that bank by altering injector amounts and timing
all the rest affect both banks but the code is bank 1 specific

P0171 is a bank 1 too lean code. Since you are only getting a code for half of the system being lean I would look towards the problem being either a vacuum or exhaust leak. If neither of those are found the next thing I would think of is a plugged or faulty fuel injector. If its plugged there are some good injector cleaners that can help. Don't by the cheap $5 stuff you would need the really good potent stuff.

System too lean, bank 1.

code p0171 refers to system too lean bank 1===causes ---intake /exhaust manifold leak---ARI system--MAF/VAF sensor--fuel pressure /pump---injector/s---ECM
code po172 refers to system too rich bank 1===causes --intake blocked---EVAP canister purge valve---fuel pressure---EGR system---injector/s---HO2S

It would help if you could get the car scanned with vag-com, it will show the full fault code.

P0171/ Fuel Trim; Bank 1: System Too Lean
Possible Causes

* Mass Air Flow Sensor defective

Possible Solutions

* Check Mass Air Flow Sensor
* Check Fuel Pressure Regulation
* Check Fuel Pump
* Check Injectors
* Check Intake System for Leaks
* Check Exhaust System for Leaks
* Check Secondary Air System for Leaks
* Check Vacuum Pipes for Leaks

P0171 means: System too lean (Bank 1) P0174 means: System too lean (Bank 2). Sounds like your injectors are not getting enough fuel.

Code PO171- Lean mix of Bank 1.
Code PO174- Lean mix of Bank 2.

Most of the time a P0171 and P0174 is caused by either a vacuum leak--more than likely the PCV hose and valve or a dirty or defective Mass Airflow (MAF)sensor. Low fuel pressure can also cause this condition. The PCV hose is located on bank one but can affect both sides because the other end is located on the back of the upper intake manifold. Usually they deteriorate and get a hole in it.

Clean the the MAF sensor with MAF cleaner, which you can pick up at any Auto parts store and also pick up a bottle of fuel injector cleaner. Good luck and hope this helps.

system too lean in bank 1. clean your mass airflow sensor, replace fuel filter. iff all else fails check you fuel pump.

see if catalyc converter is clogged it will make a car idle and run bad