MB-03

Hello! My 2010 venza with 132,000 km's recently had it's check engine light, VCS light, and AWD light come on. I pulled the code and it came to P0051 and on August 8 Bank 1 Sensor 1 went out and I had to get it fixed by a shop for $750. Before that I had to do wheel bearings and rear sway bar. I bought this car this year around February. Do you think I may have bought a lemon or is this normal? Thank you!