I recently had a check engine light on my 99 ranger, did a read, and it came back as P1451 (EVAP control system). I diagnosed the problem as a bad canister vent valve solenoid and replaced the part, I checked the gas cap too but that was fine. The check engine light remained on after driving for about 80 or so miles. So, I scanned it again, and I got the same code, but after disconnecting the reader the check engine light went away.

Now my question is, did scanning it again after replacing the part help to clear the code off the computer? I didn't manually clear anything myself, but I was curious if I actually fixed the issue or if I should expect the check engine light to come back on again soon?

 

EVAP system takes the longest to clear, because the computer has to test the system twice on two different drive cycles in order to "pass" the system as repaired

Here is what the computer needs to "pass" emissions testing and clear an emissions code: Ford Motor Company Driving Cycle

1 drive cycle is engine warmed up above 160degF(closed loop) for a few minutes or longer, and then allowed to cool down below 130degF(open loop)
Next startup would be drive cycle 2
There is no way to force any test, parameters must be met and then computer will run its tests on the different systems............in its own time, lol.