Just because it spit out that code does NOT means that sensor is bad. It
basically said that there is a problem at that corner of the engine. Over
Retard... can mean a lot of things... why is the engine over retarding the
timing at that corner but not the rest of the engine?
Bad fuel? Lower octane fuel will cause engine to retard timing... but just
that corner? What is the mileage of the car? Spark plug changed? Fuel
injection cleaned? Maybe something else.
My suggestion is continue to search on internet about this issue... someone
must have ran into this problem and posted their solution.