Mercedes Benz

While codes P1455, P1456, and P1457 can relate to the A/C system on some vehicles (specifically Porsche), they are more commonly manufacturer-specific codes for the Evaporative Emission Control (EVAP) system, especially on Hondas. You must determine your vehicle's make and model to diagnose the codes correctly.   For the Porsche Boxster In some Porsche Boxster models, the codes relate to the A/C compressor control circuit.   P1455 A/C Compressor Control:  Indicates an open circuit. P1456 A/C Compressor Control:  Indicates the signal voltage is above the upper limit. P1457 A/C Compressor Control:  Indicates the signal voltage is below the lower limit.   Possible causes: A faulty A/C compressor clutch or relay. A short or open circuit in the A/C control wiring. A malfunctioning powertrain control module (PCM).   For Honda vehicles On most Honda and Acura models, these codes indicate a leak in the EVAP system, which controls fuel vapors.   P1456 (Hon...