The code B1315 comes for the fault of the engine. If you get any problem in the car engine, then you should take it to the engineer. The engineer can identify the problem quick when he gets the model and manufacturer of the engine. It is not very difficult to solve the problem to understand the meaning of the code. B for Body Code Problem is antilock brake system, electronic suspension and steering systems. 1 for MFG – Manufacturer Specific. 3 for IC Module 4X Ref Circuit Intermittent, No Pulses. 1 for Low Coolant Circuit and 5 for Park and Neutral Position (PNP) Switch Circuit Engine Torque Signal Circuit.