My 04 RX300 with 142k on the clock and regular servicing (mostly with Lexus) is now off the road and at Lexus Poole with a snapped camshaft. Initially, the RAC diagnosed an OBDII code of PO345 said it was a failed camshaft sensor which I changed with an OEM part. The problem was still there and so 2 days later, the RAC recovered me from my home to the Poole dealership. They found a broken camshaft on bank 2 (nearest the radiator) and £700 to fix it. What will follow the successful running of the engine will be a replacement timing belt.
My question is: Why would a camshaft snap? Metal Fatigue, or what? Has there been a history of camshaft failures or recalls for this part?