Volvo: 90 240 dl service light, oxygen sensor, immed

Question
i have the the 90 240 dl... the service light comes on immed. with starting the engine but turns itself off after a couple of minutes... does this after every start and stop of eng/ignition even if it has just (the light) has turned off, i turn off engine, i start up engine, light is back on for another couple of minutes... just bought it and the owner before had cad. conv. replaced...passed immissions but with slight problem on the first read...

what do you think ?

thank you,

Aaron

Answer
It sounds like the computer is getting a failing signal from one of the sensors that relate to the engine warming up.  I could be the catalytic converter, or something like the oxygen sensor.  The latter could especially  be the issue because that would cause problems with intial smog readings as well.  You could have those sensors checked, or have a shop run the computer for error codes, but to be honest, if the light goes off eventually and you passed smog, you're probably all right.  I might wait until the light doesn't go off, because then you might get a computer error code, and better be able to have a shop track down the problem.  Hope that helps.