NEFF Dishwasher won’t complete cycle – S51M53X0GB/28

I’ve searched online but not really found anything that exactly matches this issue…

A fast cycle (29mins) seems to get stuck around 16mins. The light will go off and then back on again in approx a minute – but it doesn’t really advance any further. It even went back to 22 minutes. The water did drain away and it was hot inside but it had clearly got another 16mins of the cycle to do. I presume this was the final rinse and heat.

A eco cycle (220mins) seems to get stuck around 30 mins to go. So again, stuck at the final hurdle.

I’ve run a rinse cycle (15mins) to confirm the pump is working OK and that finished as expected on time and all the water has gone.

I’ve checked the impellor on the drain pump and no sign of blockage or fouling.

Various post suggest a heater issue caused by a faulty relay on the control module. I had a look at the heater relays and no visible sign of damage – but they are sealed so not much to see. Some posts indicate that the 10A relays were not high enough rating for the 10A heater – but my control module actually has 12A rated relays – so they have maybe redesigned the board based on feedback.

It points to control module issue but I’m reluctant to do this atm as they cost £167 (assuming I fit it myself) and I’m not confident it will actually fix it.

Does anyone have any other suggestions on what the problem is and anything I can test?

Cheers