They test for Hydrocarbons, NO, and CO. Everything else was well below the max level. The CO level was just over the max. Any suggestions before I go for my re-test.

Thanks in advance

A 1984 4000S quattro

that you need a voltmeter with a special connector to splice into the differential pressure regulator sockets to get the duty cycle reading. aside from the type of meter and the way it's connected, the procedure is pretty much the same.

Adjustment can be done with plain wire, no "special" connector needed.

An 1984 4000 has "mechanical" CIS, with the warm-up reg.