I have a 2001 Neon with 38,000 km. While driving the check engine light came on and the temp gauge was at the top.
I checked the fan was running and the coolant temp was normal. No overheating.

I checked all the fuses - OK.
I read the codes - P1684 -batt. has been disconnected in last 50 starts.
P0443 Evap purge solenoid circuit.
P1490 Low speed fan control
P1496 5 volt supply too low

No codes for coolant related.

I tried to disconnect the engine coolant sensor to see what the temp gauge did (it reads lowest when key is off and goes straight to highest when key is turned on) but I can barely see it or touch it and don't know how or where on the plastic housing to disconnect it. (I don't want to start prying it and break it.)

I disconnected the battery to reset the pcm and got 2 codes 1684 and 1496. But didn't drive it so other codes may come back.

Here is my question - there is a small shop next door and a Chrysler dealer close by. Is the small shop likely to have the tools and knowhow to fix it? Is there any chance it could be the PCM which should still be under warranty which would mean I should take it to the Chrysler dealer?
Would fixing the gauge/temp sensor clear the trouble codes. (it's hard to start and slow to accelerate).