The engine C1874 Code is a short definition and it is Air Suspension RF Air Spring Solenoid Output Circuit Open. The car C1874 engine code is a kind of chassis problem what is not difficult to solve. The automobile dictionary meaning of the code is not helpful and it is C for Chassis Code Problem is controller area network wiring bus and modules. 1 for MFG – Manufacturer Specific. 8 for Ignition System Or Misfire. 7 for Vehicle Speed Output Circuit and 4 for Cruise Vehicle Speed/Set Speed Difference Too High. You will get the real meaning from the car engine manual.