My 1985 740 GLE failed it's emmisions test last week. The CO levels were three times the legal limit, and the HC levels were pretty high also. Strangely enough, the NOx emissions were safely in spec. At any rate, they failed me for ignition timing also (error "B06"). I am assuming due to the large amounts of Carbon Monoxide that my Catalytic Converter is dead...could that be caused by my ignition timing being bad? How do I adjust the ignition timing in this car? I hear that it is controlled by the onboard computer

By the way, this car passed the emissions testing last year with flying colors.

Thank you in advance,

Calista