Keston C36 Combi boiler - E03 error daily

24 Jan 2023
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United Kingdom
This error code appears daily when the shower is in use in main bathroom (and abruptly stops hot water)
It works fine if I use shower in second (ensuite) bathroom.

On the website it says "E03: Overheated boiler".

(It might be true as the water in main bathroom comes out real hot! Even if I move the tap 1degree towards hot side the water is super hot. On boiler the temp goes up around 75-76 in such case)

What concerns me is if this issue is with boiler or with the plumbing?
(Sometimes it do show the same error code while heating is turned ON, but rearly. Maybe one/twice)

What could be the real issue here?
(The boiler was serviced 6 months back when I moved in here but the main bathroom wasn't in use until recently, so the issue might be there since forever)
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If it’s only doing it on the one shower and all other outlets are fine, I’d be looking at a blocked shower head/hose. Perhaps try it without or with the hose from the other shower?

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