C1286 Booster Mechanical Failure?

Has anyone come across this problem before?

Car is a 2003 S-Type, 3.0L V6 Petrol.

For quite a while I had an ABS sensor issue which resulted in the ABS and DSC lights coming on and occasionally the car would go into limp home mode. it would only go into 2nd or 2rd gear and stay there. I eventually replaced the rear left sensor and now the car drives fine, changes gear properly and the ABS warning has gone, however, as soon as I changed the sensor I started getting this new error which I have not seen before. Also the DSC light comes on again after about 3 miles. 

So the new error is C1286 Booster Mechanical Failure. That is the only error now showing. No errors regarding the DSC warning light. 

Is this pure coincidence? That C1286 error showing just after I changed the faulty ABS sensor? Where can I look to find out what is causing it?

Also why no errors regarding the DSC light and why does it only come on after approx 3 miles? Actually on the last run it came on after 3 miles but I parked up. Went to the store and then drove home another 3 miles but the light didn't come on. Before the warning light appears I CAN turn the DSC on and off as normal. 

Any suggestions on what the issue could be?

Many thanks.