Other than blowing some air through it you really can't clean it. It's an optical sensor and trying to clean them usually results in catastrophic failure; In other words, you'll be buying a new one.
The cause of a code 31 could prevent the car from starting and running. With the wiring for the CPS being jacked up, I would be surprised at all if that was the case in other areas as well... How did it get messed up to begin with, do you know?
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