how do I remove fault code from Miele wahing machine?

The soak/prewash light is flashing following a check drain and check inlet light flash. Drained the pump from the front-nasty black gunge-removed drain outlet pipe and it was full of black smelly gunge-thoroughly cleaned this, replaced. Checked and cleaned both end of inlet pipe and filters. Followed the sequence to remove the soak/prewash light but to no avail. Drums spins fine, front of pump appears free ie impaler moves round.
Used a washing machine cleaner prior to fault but check drain light had flashed on previous two wash cycles.