P0401 LOW EGR Flow Checked EGR Valve, replaced stuck EGR Solenoid Code returns on 1996 Mazda B2300

Checked the EGR Valve and found no leaks and no restrictions and it works. Checked the modulating Solenoid, found it sticking and replaced it. Vac lines also checked OK. Where do I go from here? How do I troubleshoot? Truck runs fine except for the light but I have an emissions inspection to pass by years' end.

by in Crawfordville, FL on December 04, 2012
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1 answer 3 comments
ANSWER by , December 04, 2012
possible clogged EGR passages.
COMMENT by , December 05, 2012
Removed the EGR Valve and the passages were without any buildup. Valve cycles when the vac line is sucked upon. Solenoid was stuck so was replaced. Is there a way to test the flow sensor? Where would I find the "A PCED" troubleshooting info for this problem? (Someone provided this data for an evap canister problem.)
COMMENT by , December 05, 2012
Larry...when I said EGR passages, I meant the passages on the intake manifold...not the valve itself....anyway, there is no A PCED whatever and you don't need an EVAP diagnosis.
COMMENT by , December 05, 2012
Thanks, that must have been just a location of a page. The evap was a different code, fixed with solenoid, I think. Is there a way to check the EGR flow sensor with a voltmeter? I noticed the three leads (ref, ground, signal) that could be metered, but what values should I see?