Westinghouse F5 error code

[gearbox92]

Hi, 

I have a WSF6606x intermittently throwing a F5 error code. It has done complete washing cycles recently, but is now stopping mid cycle more often. 
 

I’ve tested the inlet valve and it is working perfectly. I’ve pulled the wash motor and it’s not jammed or blocked. I’ve made sure the diverter is free and working. 
 

Could anyone suggest anything else I can check? Maybe a sensor or something?

 

Thank you!