possible answers?

2000 300m - engine light on, appears "stuck" in 2nd gear, no speedometer. would like to have some ideas of what this might be before I hit the mechanics. thanks much.

With the 42LE transmission. It sounds like the output speed sensor (OSS) may have quite working. Would be good to check computer codes or monitor computer live data to see if it has a signal to PCM/TCM.

I paid about $300 to my local no-star dealer for something I could have done myself for under $50. It is an easy item to change out. It is either the input or the output speed sensor. If you have any mechanical ability you can do this yourself. Find out from your dealer what the cost of these items may be. We will be glad to walk you through it.

There is a good chance it will not throw a code, so don't be alarmed. This sensor fails on quite a few "M's" and is a common item.

It definitely sounds like the output sensor like RexNfx400 said. You will need a 1" open end wrench and about 30 minutes to easily change it out. It is plastic, so when you go to snug it up be careful - just snug it. It has an "O" ring to do the sealing, so don't strip it.