There are so many people who are asking about this code I helped my son who owns a 1999 Honda Prelude this code came up and it is not listed in the Chilton's Reair Manual. This code is a CRANKSHAFT POSITION SENSOR it is located behind the harmonic balancer pulley or it is called a crank damper you need to have a special holding tool to keep it from turning while taking it loose. I hope this will help many people who need to know what this code is. Replacing the crankshaft position sensor took care of this trouble code. My son is thrilled that his car is fixed and running like it should.

 

The P1399 is a random misfire. The the cause of this code is another issue, multiple things can/do set this code.