Thanks for the replies. The error code description didn't give more details and no voltage indication despite the lights being on during the scan.

The only other details noted with the error code was the following:
Software version: 14/97
Hardware version 211
Diagnosis detection 1/00

Light bulbs were changed in September 2014. Bulbs installed are currently Osram Xenarc Cool Blue Intense DR2 P32D-3. Great bulbs and light by the way.

I'll try switching bulbs left to right and check from there if the problem continues.