Why am I getting a CEL code of p0171

Question

Just had the water pump and timing belt replaced last week.  Before that was the thermostat and radiator.  Now I'm getting a code of p0171.  Did not have this code before why am I seeing it now?

Answer 1

P0171 Fuel trim lean Bank 1

Vacuum leaks are one of the most possible causes for this code condition, This code does not mean it is something major with the engine it can just be some simple vacuum that has disconnected,