Knowing the correct meaning of the engine U1798 Code is necessary and the automobile meaning of the engine code is online but do not use that meaning. The automobile meaning of the code is general meaning and it is U for Network Code Problem is climate control system, lighting, airbags, etc. 1 for MFG – Manufacturer Specific. 7 for Auxiliary Emission Controls. 9 for Crankshaft Position Sensor Circuit Performance and 8 for PCM Stack Overrun. Do not drive the car with any problem in the car engine and do not follow wrong meaning of the code for solving the car engine.