Question

My car reads code P0171 what does that code mean on a 2004 Cadillac SLS V8?

Answer 1

This code means that bank one is lean. Usaually this can be traced to a faulty O2 sensor, or an intake manifold vacuum leak since it is only on bank 1.Lean condition means to much air in the air fuel mixture

Answer 2

P0171 CADILLAC - Fuel Trim System Lean Bank 1
Read more: https://www.autocodes.com/p0171_cadillac.html