I had a problem with a cracked breather tube that made the car run poorly, replaced tube and now it runs fine. While it was running poorly I had an extremely heavy breaking situation, felt a pop in the front of the car (like I hit a pot hole) and am now getting gearbox fault and P1637. to be sure i got all of the low hanging fruit, my brakes and fluid were low, replaced the brakes, pumped up the system disconnected the battery overnight and the P1637 still comes up immediately on start up after erasing with a scan tool. Car is running in third gear only. Is there anything else to try before it goes in to the dealership? I'm thinking perhaps the ABS control module? Or a tranny problem?

 

Also, I have no spedometer if that changes anything.

 

Not to Revive a old thread but, I'm having the same exact issue. Would either PJ or any other members chime in?
I did the Focus ST225 brake upgrade and I'm stuck in this dilemma now.