code 51

I have a 94 Geo Metro for the last year or so my check engine light has come on and i get a code 51. What is this code and what needs to be looked at?

Thanks

EGR vacuum switching valve solenoid.
Book says:
"Closely check all vacuum hoses to the throttle body and the EGR valve. Also check the MAP sensor vacuum hose for leaks or restrictions. In "closed loop" operation with EGR enabled, the ECM will periodically turn "OFF" the EGR VSV. If the corresponding manifold pressure change is less than a calibrated value, the ECM determines that a falult exists in the EGR system and sets a Code 51"

Thanks

Ok I checked all vacuum hoses and I still get a code 51.
What do I look at next?

Check the coil wire, as a poor connection can cause high resistance, wh ich will trigger the code 51. Make sure its' good leading into the distributor cap. Check the cap for quality, if bad, replace the cap and rotor. If your coil isn't putting out good volts, then replace.

I recently bought a 95 Metro 1.0L 5-speed. It had several codes stored but after resetting the ECM code 51 comes up again after 10 - 15 minutes of driving.
I saw a list of codes that doesn't match what is stated above for a code 51. Can someone please post a link to an accurate list for a 95?

Thanks

I replaced the EGR valve and i no longer get a code 51

While waiting for an answer to my post, I went ahead and took the EGR valve off and cleaned out the ports. The larger of the 2 hose fittings was plugged with carbon and a drill bit was needed to clear it. (Turned by hand of course). All fixed. No more code 51.