The B1859 Code is a problem of the engine and when the code reader failed to test the engine, it sends the code for the area B1859. The problem of the code is associated with the body of the engine. You can solve the problem with the expensive machines and tools along with you need to know more information what are manufacturer name and model number. The dictionary meaning of the code is B for Body Code Problem is antilock brake system, electronic suspension and steering systems. 1 for MFG – Manufacturer Specific. 8 for Ignition System or Misfire. 5 for TP Sensor Learn Not Complete and 9 for Kick-Down Switch Failed Short.