Google search indicates that it is a problem with a printed circuit board. It seems to be very common and is probably a good reason to avoid buying this boiler!!!!
I can't vouch for this yet, as I've only just got the problem myself and haven't had it sorted out!
John
October 2011
If you've faced an E168 fault, either as an installer or a consumer, please sign the following petition. Please also pass on this petition link to anyone else you know that has suffered this problem. http://www.ipetitions.com/petition/e168error/
Stuart Wilson
April 2011
e168 is pcb failure.
DAVE O
December 2009
Table of error codes as follows
e20 central heating ntc fault
e28 rue ntc fault
e50 hot water ntc fault
e110 safety thermastsat operated
e119 water pressure switch not operated
e125 circulation fault primary circuit
e130 rue ntc operated
e133 interuption of gas supply or flame failure
e160 fan or wiring failure
No e 168 sorry
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