[rogers2000]

I have a Bryant plus 90i furnace that stopped working. Upon inspection, the flashing lights showed a 42 which states that the inducer outside valid speed range. I replaced the inducer motor, main control board and the 2 stage pressure switches. I also pulled a rag through the exhaust PVC line to make sure it was not plugged. Reset control board as instructed by manufacture and lights still blink 42. I then took apart all the drain hoses and made sure they were not plugged. Still the same code, 42. Since all of the major parts were replaced with new ones, I am at a loss as to what to check next.

[Grady White]

I too am at a loss other than to suggest you check incoming voltage. It should be +/- 120 volts AC. If it is over 130 or less than 110, call an electrician.

Last second thoughts:
I wonder if the heat exchanger is plugged. If it is, it would cause an air restriction & could throw the inducer speed off.
If you have an air intake pipe, check it for blockage as well.
Make sure no hoses are cracked.