I get three red flashes from the furnace after an attempt sequence when the t-stat calls for heat. The motor starts, and seems to try to light but after about thirty seconds, it quits and gives the error code.

I have removed both gray tubes from the pressure switch and made sure they are clear of obstructions. I have blown/sucked slightly on them to hear the 'click' from the pressure switch.

I have 'jumped' (?) the pressure switch with a paperclip (having removed both wires and using the exposed contacts) and it won't fire up then either.

I have also removed the burner cover and tried to start it but while it didn't work initially, it did start later (the only time it's worked since initially giving the error) with the cover off, but this could've been due to messing with the wires on the pressure switch?

Does the "jump" experiment indicate a BAD pressure switch and a new one would solve my problem? This is only a 3 year old furnace!

Please help!