Both lights remain on even though I'm charging well and the O2 reset switch has been checked.  New alternator just fitted, charges at 13.8V.  Thanks to Lawrence for leading me to the D+ wire on the aux. battery relay under the seat, when I disconnect this wire both lights go off.  I've checked the following:  The relay (including it's inbuilt diode),  both the diodes on the instrument panel, no problems found.  Incidentally, if I disconnect the O2 sensor plug underneath the van it obviously deletes the O2 sensor light but does not affect the Alt. warning light.

It seems to me as though when the aux. battery relay engages it's somehow "taking away" the D+  from the light and allowing it a path to Bat-??

Any ideas??

Martin Wilson