what to do when coolant is detected in the oil

Question

what do I look for when coolant is detected in the oil?
Codes 171 & 174 came on
2004 suburban 5.3l z

Answer 1

P0174 Fuel trim lean Bank 1

P0174 Fuel trim lean Bank 2

Coolant in the oil can come from the intake manifold,  The solution is to replace the intake gasket.