Hi Guys! I have a 94 GMC Sierra 5.7. Seems to run really well but recently failed emissions.
SES light comes on after truck has been cruising at higher speeds and is warm. SES light goes away when car is off and won't light up again unless I'm cruising on the hwy for a certain amount of time as mentioned above. I pulled OBD codes 32 and 34. I understand that this could mean a faulty EGR valve and bad MAP sensor or issues with vacuum/wiring at those sites. Is there anything I am missing? I understand that EGR switch should ground when it senses gas and I'm wondering if it's a bad selenoid? Also, I'm wondering if a bad MAP sensor will also trigger a 34 AND 32 as a domino effect? thanks