Indesit dishwasher DVG622 lights 2 & 4 AND salt light

Stops around 15 – 20 mins into a cycle, flashing lights 2 & 4.
If you then power off and restart, it then goes straight into the error 2 & 4 again.
Heater and wiring are OK and it is heating up, so I suspected the timer.

Replaced heater relay on timer, but fault still apparent.

So suspected temp sensor and replaced timer.

On new timer fit, the salt light was then flashing, which it hadn’t been doing with the old timer. Salt level is well topped up, though.
Then after 15 mins on quickwash, lights 2 & 4 come back and it stops again, but there is plenty of steam coming out when you open the door, so it is heating nicely.

If you power off and back on, salt light then stays off – it drains, fills for 26 seconds, then 2 & 4 and salt light all start flashing again!

Anyone had similar, or know what my problem is, please?

Thanks,
Pigpen.