1995 Dodge Spirit Diagnostics

So I have a 1995 Dodge Spirit and this winter has been rough so far. My heat does not work properly at all and only really gets warm at all if it isn’t cold out or if it sits idling for like 20 minutes. Once I start moving though it blows cold air. I did a diagnostics on it and it gave me these codes: 12, 17, 21, and 52. I am not a huge car expert but I also don’t have a ton of money (hence the 1995 Dodge Spirit lol). I was hoping someone would be able to point me in the right direction as to what is wrong with my car, what would need to be done to fix it, and how much it would cost. At the very least, I want to have working heat. If it helps, I could also point out that I believe the computer in the vehicle is broken and the windshield wiper motor is as well.

Thanks in advance!

Fault 17 is Engine too cold too long, (thermostat failure).

Fault 21 is Oxygen sensor stays at center.
Fault 51 is Oxygen sensor stays below center.
Sounds like the oxygen sensor is failing.

Ok is this easy to replace? Do you know about how much it would cost? I am going to replace the thermostat myself just in case since it is really easy and cheap but I don’t know how to do the oxygen sensor.

@GohanSolo
I Owned A Spirit With The 2.5L 4-Cylinder (Good Engine And Smooth Running) That I Bought Nearly New With 6,200 Miles. I Had It Many Years And A Couple Hundred Thousand Miles. It Was A Fantastic Car, Comfortable, Reliable, Great In Snow, And Great MPG.

Is yours the 4-clinder? I would try a thermostat and I don’t recall if that’s got a bleeder valve on the thermostat housing, but either way follow procedures to vent air out of the cooling system.

Is the radiator full (check with engine cold) and some coolant remaining in the reservoir?

…"I believe the computer in the vehicle is broken…"

Please explain.
CSA

Yes mine is the 2.5L 4-cylinder. What do you mean by venting air out? I thought it was just a simple fix of taking it off and putting the new one on. Maybe I should take it to a garage…

The radiator is full but I recently had to fill the reservoir because it was extremely low. There was basically nothing in it.

I believe the computer is broken because the odometer will randomly stop working properly and will flick up and down until it eventually stays at 0. It can be fixed sometimes by turning my headlights on and off.

I am considering getting a new car as I don’t want to sink a ton of money into repairs for a car that, in its best condition, is worth maybe $600 to a dealership. If the repairs are too costly, I would just like the cheapest and easiest fix to get heat in my car until I can trade it in.

Thank you for your help!

There is a 10mm hex plug above the thermostat, remove this plug when refilling the cooling system. This will vent the air from the engine.

This vehicle has a mechanical odometer display, it can’t change to zero. You must be referring to the speedometer needle. The speed sensor is probably failing.