check engine light on 1993 Ford F-150 Lightning

my check engine light on my 1993 lightning has been on for over 3 years now.i had it checked out with my garage,an he told me the code it through was for the EGR valve.so i replaced the part myself,including the sensor that bolts on to it.an it is still lit.it idles fine a runs perfect.but the check engine light being on is killing me.what else could it be if the problem says egr.any answers to this question will be greatly appreciated.

by in Old Orchard Beach, ME on April 09, 2009
1 answer 1 comment
ANSWER by on April 09, 2009
If you have replaced the valve as I outlined in your other question I need to know how long it takes for the light to come back on. You could have a vacuum problem that is not opening the EGR valve when it is commanded open. Your vehicle should be OBD I certified, to check this look at the sticker under the hood with the emissions information on it. There is a part at the bottom of the sticker that says vehicle certified for sale in California or 49 states etc. then in that same paragraph it should say OBD I or OBD II. Disconnecting the battery as mentioned before should clear the codes, on OBD II you may need to use a scan tool to clear the codes. If the light comes on immediately after start up then there is probably a wiring fault and that will need to be traced to the source. If the light takes a while to come back on you may have a vacuum concern or the rare engine control module fault(very rare for this vehicle). Vacuum concerns range from a bad or missing reservoir, broken or cut lines, erratic vacuum solenoid or plugged solenoid vent filter.Good luck.
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COMMENT by on April 10, 2009
the engine light turns on about 10 or 15 seconds after i start to drive away.
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