The water washing system on the compressor side, code P51205-03, is a maintenance feature in the MAN L21/31 engine that enables the removal of dirt, salt, and oil build-up from turbocharger components. By injecting a controlled flow of water while the engine is running at partial load, it ensures optimal compressor efficiency, minimizes performance loss, and extends the service life of the turbocharger. This is especially valuable in marine and coastal operations where air contamination is high.