It was purchased used 4 days ago and has 81000 one owner miles. There is a message light that says " SOS drive to repair shop. Whar could this be? The car drives, runs, and rides perfect.

Not the muffler,the hole has to be before the
exhaust converter,don't you ask questions or
understand what your told?

In the future explain that you go to a mechanic
& not work on your own vehicles

Every question on this site is incomplete & applies
the owner works on every vehicle

If went to a repair shop, why did you not have ALL issues
repaired once & for all?

check tire pressure.

Is the cylinder receiving spark?
If so, then replace fuel injector.
If not, then replace spark plug, coil and lead.

replace oil level sensor

First, get under the hood and locate where the oil is coming from...that will be the place to start locating the problem. Is the oil filler cap in place or missing? Are all fluid levels where they are supposed to be? Is the vehicle running hot when you drive it?

CODE PO155 - HO2S 21 BANK 2 SENSOR 1 HEATER CIRCUIT MALFUNCTION CONDITIONS.CHECK O2 SENSOR FUSE AND WIRING CRCUIT BEFORE BUYING A NEW HO2S.IF SENSOR BAD REPLACE IT.THEN YOU CAN CLEAR THE CODE.

5K kms or equivalence in miles.

You should never buy any van type vehicle, in the first place,
the transaxle will fail any day.
I used to own a trans repair shop

Other then sell it,I would,I won't ride in one, not safe

Your correct,you should go 5000 miles and maybe use a 1/2 qt,
on most vehicles, none.

So you do a cylinder leak down test
Check Emission Gas Readings,to see what that shows
I suspect a broken oil ring,scored cylinder, broken piston
skirt or serious cylinder head issues.

Never go to a dealer. Calling or Visiting is okey

this light can come on even thought service is not actually due. if the service was performed and the light was not on at the time, sometimes you cannot reset them if they are not actually lit, or 99% of the time the technician forgets if the light was not on. stop by your shop and they can reset it for you in just a few moments, and for no charge. good luck!

Check light on , have codes checked . Transmission not shifting into a gear , could be a shift solenoid . Take your vehicle to a qualified repair shop , before it get's ruined .