Sorry guys - all bets are off as far as I'm concerned on this particular model of WB35cdi.
All the docs I have are for the one-pump version and I've only ever worked on that model and its later derivatives. Without the right refs (and apparently these are not available on the latest WB CD either!!!) I can't even tell you for certain whether the error indication means 'overheat'!!
This is actually quite a problem - if manufacturers choose to delete all reference on websites and elsewhere to older / obsolete models, without an M&I manual on-site we're all screwed!
However, if the thing has 2 pumps and no diverter valve, then a blocked secondary heat exchanger (if there is one!!) is still my favourite for the root cause of the problem. I don't understand why doitall thinks a blocked 2ndary would affect CH performance at all.
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