OK, it's emissions testing time and my car must have known, as it decided to throw the SES light. Datamaster is telling me I have a code 27, EGR vacuum control signal solenoid valve circuit. I've taken a look at my Helms manuals as well as the Haynes manual and it gives me some tests to perform. Unfortunately, I don't have a vacuum gauge yet. I plan on getting one this weekend.

This morning I removed and inspected the vacuum lines from the intake through the solenoid to the EGR valve and there appear to be no leaks. Last year when I got my emissions tested my NOx was high, bordering on failing.

From my readings on this board and elsewhere I know that an elevated NOx reading can be related to a failure of the EGR valve. Should I begin by replacing the valve, solenoid or both?

Thanks in advance,

Joe