I have a 2014 f 250 with 59,000 miles. My check engine light just came on, and I put my code reader on and it shows P20A1, reductant purge valve performance. I am wondering if I let this go very long if it will limit my speed or not. I replaced both the DEF heater and pump unit that sits on top of the tank less than 5000 miles ago. Hopefully I don't have to replace the pump again already. Anyone else have this problem?