'90 accord ecu code 43

Hi all,

My 90 accord has about 255,000km, it drives great and it's been
maintained well.

A few days ago, my engine light came on while driving < 60 on
a downward slope in town. Now the light comes back consistently at speeds
over > 80 when I drive on the highway. I've reset the ecu with no avail.

I get the ecu code 43. I see 4 long flashes, 3 short ones followed by a
pause, a short flash and then everything repeats again.


Some people on the newsgroup mentioned a potential oxygen sensor problem.
What are the costs (parts and labour) for this kind of problem in Canada ?

thanks in advance,
-Vlad