First problem was false flame code 5 inducer motor running every 10 minutes or so with t-stat off, so replaced the circuit board now I have code 3 pressure switch failed to close checked switch with inducer blower running I have continuity through the switch what else can be the problem

Please describe in detail the methods you used to check continuity through the pressure switch.

Check to be sure you have the correct wires connected to the pressure switch and circuit board.

Are there any other switches on that circuit, or does is the pressure switch the only thing on that circuit?

Checked for continuity at the switch with inducer motor running and wires off switch and had continuity.