2004 Suzuki Verona with engine codes P0171 and P0174

Question

What if we have done all of this and the check engine line is still on and still showing codes as P0171 and P0174

Answer 1

P0171 Fuel trim lean Bank 1

P0172 Fuel trim lean Bank 2

No vacuum leaks at all? Vacuum leak are the main reason for lean condition. If you are sure of no vacuum leaks  Check to  see if the ECM was reprogrammed for the adaptive fuel control logic. which is lean enough to cause engine stalling. At one time Suzuki produced a TSB for a Recall to reprogram the ECM for running lean condition which could stall the engine during deacceration.  TSB # TS02

Answer 2

P0171 Suzuki Code - System Too Lean Bank 1
Read more: https://www.autocodes.com/p0171_suzuki.html

P0174 Suzuki Code - Fuel Trim System Lean Bank 2
Read more: https://www.autocodes.com/p0174_suzuki.html