Code P0172 both banks running rich.

Question

I changed the air filter, cleaned MAS sensor. In order what should I do next?

Answer 1

P0172 Fuel trim too rich bank 1,

Cleaning a MAF sensor is need due to running lean condition, when the MAF is contaminted ,the powertrain runs lean,  What causes rich condition is compression being low, which is a mechanical problem,  Another cause of running rich condition is a fuel pressure regulator, If the vacuum hose to the fuel pressure regulator is ruptured, you will have a running rich and lean code. So you need to inspect that hose,use the under hood vacuum daigram,A fuel injector that has a bad spray pattern can cause running rich on that particular bank. The PCV hose on Ford it tends to fail which can cause running rich problem,or if its plugged up.