He may have damaged the O2 sensor when doing the repair. Try replacing it. I think Volvospeed has direction for clearing codes. The link is on the main page of this site.

I suppose this is a really wierd problem. I'm sure it's just a lose ground somewhere. Damnit, I need a wiring diagram.

I have a '93 850 GLT with a 5-speedand 171k miles. The car seems to run fine, but when not moving the temperature and fuel gauges drop to zero. As soon as the car moves (and I mean less than a crawling pace), the gauges come back on and work normally.

The most annoying part in all this is that it ...

Andrew,

You asked about the humming coming from aournd the TB/ETM(whatever) and everyone seems to have ignored it.

The sound is normal. The Idle valve works with a ~60Hz pulse width modulation. That's what's causing the sound.

To everyone else,

Great info. I have a few things to try to fix the ...