In checking the reason for engine light on, I was pointed towards the egr system. to cut to the chase I back probed the wiring at the back pressure regulator and got the .46 volts it says in the manual. it apparently is supposed to raise to around 1.2 volts at about 2,000 rpm or when the engine gets hot. it never reached anything high than .46 volts does that mean that the regualtor is bad. Also they said that the coolant temp sensor came up as a fault. I check the signal voltage from the pcm and got 5.0 OCV ohmed the sensor at cold temp got about 65,000 ohms. as the vehicle warmed the resistance went down to 2,500 ohms is 65,000 ohms to high for the cold sensor. They erased the code and it didn't come back on one driving cycle. I jsut want to be ready if it pops back on. any one???