[rogerthechorister]

Fresh test done without charge. The correct test.

Lambda perfect at 0.14 first test and 0.997 second test.

HC perfect. 200ppm is allowed and I have 26 first test and 19 second.

CO disaster. 0.3 is allowed at fast idle and 0.5 at natural idle, I have 1.12, 1.00 and 0.93.

So, too rich.

Garage says most likely air filter, then spark plug then air leak then exhaust leak then AMM.

California smog advice adds o2 sensor (sounds a fair bit like the way a lambda sensor works) a MAP sensor which I have never heard of, TPS which I think is a simple switch on a 1996 940, and ECT - unlikely in that temp gauge is sitting bang in the middle although I think she has two, one for the gauge and one for the ECU.

So I will order air filter, dizzy cap, rotor arm, HT leads and plugs (which I had been planning to do anyway). I have an unused AMM in stock. Some of those bits I can do myself mostly for fun - and I could do an Italian tuneup too.