So i had this error code after a check engine light popped up seemingly out of nowhere. Engine seemed to be running fine. I took it to a garage and they said most likely spark plugs. We had a look and the rav had 4 mismatched spark plugs in so i changed them to see if that was the problem. About 250 miles later check engine light again, same code. I was in a different town and the engine appeared to be running fine, so i went to a garage and just cancelled the light. No problems since but im just waiting for the check engine light to show its ugly face once more. Any suggestions as to what could be the problem?