Hey all.....I was getting an "OY" error message on my Buderus GB142 - supply side water temp exceeding 199 degrees.....my heating guy replaced the pump for the DHW with a larger pump and it has not gotten the "OY"...it reaches 196 which I think is still high....wondering if this was truly the problem or the larger pump is somehow masking the real problem...i.,e supply sensor going bad? Anyone know would a supply sensor give false readings or would it just completely fail?

I have 4 zones - DHW, Air Handler zone, basement zone and garage zone....not using any of the last 3 for several months because it was summer....

Any ideas would be appreciated....