Hey guys

Since yesterday, it shows up with a service light on dash and then doesn't rev over 2,000 revs. It happened yesterday whilst driving. I parked on the side. Turned the car off and on, it was all good then. Today just now, it did same again. Turned the car off and on about 3-4 times the car being off for about 5 secs each time made no diff. Drove to petrol station to check tyre pressure, turned the car off, checked pressure and back on and it was perfectly fine. What could this be?

Also tyre pressure on standard veccy alloys and tyres ie 215-50-17, what should the tyre pressure be?

Cheers guys