The meaning of the U1012 Code is U means Network Code Problem is climate control system, lighting, airbags, etc. 1 means MFG – Manufacturer Specific. 0 means Fuel And Air Metering. 1 means Low Coolant Circuit and 2 for A/C System High Pressure High Temperature and it is not very helpful. The U1012 engine code appears a kind of network problem. Like the all car engines, this car engine system services especially established hydraulic lifters for the U1012 code intake and finish valves. The lifters can be distorted by disengaging an inner locking pin. The locking pin is severed using solenoids to change oil pressure fed into the lifter.