I have a Daikin Altherma air source heat pump installed and has been running fine for the past 2 years. A couple of weeks ago it gave an error - 7h

The fault code states - 7H indoor unit LT: Flow switch activated water flow rate too low or blocked inlet strainer

I have cleaned the strainer in the pressure reducing valve this evening and will wait and see if it has cured the problem - it was slightly filled with rubbish.

Here is my question: when the error 7h was displaying and I pressed the "Test" button once on the control panel, this was displayed: -

160
7 2-


and if pressed again, this is displayed: -

160
7 J6


Are these further clues as to what the problem could be?

J6 Error code is Outdoor Unit LT: Malfunction of thermistor for outdoor heat exchanger.

The model number for my unit is: EKHBH016BA6V3 and EKHWSU300B3V3

Thanks,
Simon