I FINALLY got the 960 on the road. What a wonderful car! It is getting new struts/mounts/bushings next week and will be ready for a good road trip. Except for one little glitch... The check engine light comes on about every 20 miles. It give the 2-4-1 code which is the EGR booster. I have checked the EGR vacuum and it holds perfectly. I also checked the vacuum lines and they seem tight. What gives on this? The lines lead out of a white electric box on the fender. Is this the culprit? Or, do I have a vacuum leak elsewhere? The light seems to come on after I've really revved the engine good.

Any "light" on this light would be GREATLY appreciated!

I can give you what information I have from the service manual
There appears to be two potential problems that will give the code. The first is a flow malfunction and the second is leakage.

Flow malfunciton: If the ECM sends out a control signal to the EGR vacuum controller and EGR temperature sensor signal is not changed, the ECM notes this as a fualt and DTC 2-4-1 is set.

Leakage: If the ECM notes that the EGR temperature senor has changed by more than 60mV before the ECT sensor has reached 60C (140F), the ECm notes this as an EGR flow occurring when it should not and DTC 2-4-1 is set.


Problems to check out that will cause a flow malfunction.
Signal lead short circuited to live
Break in signal lead
Break in power lead
Bad contact or contact resistance in connectors
Defective vacuum hoses
Defective EGR-vacuum controller
Defective EGR Valve

Problems that will cause leakage
Signal lead short circuited to ground
Defective vacuum hoses
Defective EGR-vacuum controller
Defective EGR Valve
Defective thermostat in engine coolant system. If the engine dosen't reach working temperature within a given time, the engine compartment temperature can affect the EGR temperature sensor enough for the signal to the ECM to change by more than 60mV.

When you rev the engine due you feel vacuum pulses in the EGR controller. Pulses means the controller is operating.

There are another 10 pages associated with this DTC.

I just knew it couldn't be something simple! Jerry, thank you for all the info. Several of these things I've ruled out as the Vacuum holds good on the sensor from the vacuum line. I loosened and reconnected all the electrical connections yesterday to make sure everything is making good contact. When the check engine light is ON, it's very hard to start when cold and runs really rough.

After clearing the computer again yesterday, it has been doing very well...although I've only been about 10 miles of city driving. The mechanic switched all the old EGR system onto this engine and the check engine light was NOT on before. So, I'm hoping it's a connection or such as that EGR valve is a NIGHTMARE to get out of there. I'm assuming the intake manifold has to come off as I can't even get my hand to the entire unit.

Thank you again for the information. I probably need to buy a service manual for this car and keep it myself. I can just see my 75 year old mother out under the hood diagnosing the computer codes!