I've had the same problem on my Indesit (IDL-730, IDL730) and after pouring in salt until full for ages, without the light going out, I finally decided to do the reverse.
I left it to run down the salt over a couple of months, until well empty (not ideal, but I was getting desperate!), and then finally refilled it.
Problem solved - salt error light was no longer on
All I can figure is that a blockage had set in and casued the issue. Leaving it to clear over time sorted it.
Hope this helps in your situation.
Kevin Rustill, November 2007
