i have 2 obd codes of PO174, and PO401 i had my car repaired twice on 1999 Mercury Sable

My car has been serviced three times with the first repair for code P0401 where all my EGR sensors were changed, engine light stayed out 1 day, light appeared back on ,had it checked code P0174 shows up with code P0401 mechanic checked it again said he had to clean vacuum hoses, ok engine light out for 1 day appears back on on 2nd day ,i also failed inspection iam ready to throw in the towel i have 30 days to have repairs done before re-inspection ,what should i do next please help the car also has a burn smell .

by in Newark, NJ on April 25, 2012
1 answer
ANSWER by on April 25, 2012
po174 is system lean bank 2 and po401 is egr insuff flow. the 1st code needs to have a smoke test to find possible vaccum leak and the other is possibly the dpfe valve or hoses going to it are disconnected or broken