I have a 1996 Ford ranger 4.0 and the check engine light is on. The codes are 401 and 402 egr flow insufficient and excessive, is this a bad egr valve or something else ?
You will need to replace the egr valve, the egr regulator and the Sensor. Order all three from a Ford Dealer, replace all three ( make sure the lines are clean ) and you will no longer have this problem. This is what we do at my shop and seems to work each time. It shouldn't take 30 minutes to replace them. Buy the parts before starting the project. The vehicle can be driven without worry of damage to the engine.