Do not drive the car when you detect any problem in the car engine. You must fix the car engine by the right way but before that you must check the car engine and know the reason of the car engine problem. This engine P1581 Code is found from the car engine by the test of the car engine. The automobile dictionary meaning of the car engine is p for Powertrain Code Problem is related engine, transmission and emissions systems. 1 for MFG – Manufacturer Specific. 5 for Computer And Auxiliary Outputs. 8 for Exhaust Gas Recirculation System Valve 1 and 1 for TFP Valve Position Switch-Drive Without Drive Ratio.