If you are seeing 16 Bar when the compressor is running, then there is nothing wrong with your compressor. It’s working to spec (<8 Bar seems to be when codes become more regular, eg overtemp, implausible pressure signal, low ride height etc). When the compressor shuts off, the pressure in the supply/exhaust line will naturally bleed off via the non-return valve and exhaust solenoids located within the compressor assembly. At that time the sensor is only measuring the pressure in the supply/exhaust line from the compressor, nothing else. This residual pressure reading is pretty much irrelevant and has no bearing at all on system performance.