The meaning of the trouble C1931 Code is very important thing and if the right meaning of the code is not available, you should not try to solve the car engine problem. The general meaning of the engine is available online but those are not perfect to follow for the car engine problem. The automobile meaning of the engine code is not compulsory to use. You have to rely on the right meaning of the engine code and it is found in the car engine manual. You must not drive the car with engine problem and you should be careful about this problem.