Let me describe an issue this sensor will create in case your car isn't starting, its cranking over but won't fire.

If you can see the Coolant sensor temp reading, Scanmaster or software, and it shows...

312 (anything really really high)

This might trigger a SES Code 21 (1G code)

Your ECU will not allow enough fuel to start up the car. This sensor will cause a no start if its damaged, ya it's a sneaky sensor that won't be on your radar.

WHAT TO LOOK FOR...

These sensors have 2 male spades that are fixed in place by a rubber molding. Over time the rubber softens and then if you go to unplug the sensor to swap thermostat housings/head gasket etc you'll pull a spade out of the molding and it won't make solid contact inside.

One possible solution...
After swapping in the new sensor, consider...
1) Soldering the males onto the female connectors
2) About 2" down, add onto those 2 wires a barrel end connector for easier on off access without pulling on the males directly. Hold the wire tight behind the barrel (male side) then pull the opposite side so there's no torque applied to the male in the rubber.

Our buy an extra sensor and have it in your cars DSM parts bag.

Sensor below is the Duralast version like $18, but I'm waiting for my OEM from Amayama to arrive, Duracrap will be my back up.

Update

Amayama does not have the OEM Coolant sensors either, the website will allow you purchase the item, then they check and I got confirmation it's discontinued/no stock for them too. Damn

I guess it's Dura-not-last to the rescue for maybe 10k miles.

You can still buy the NTK EF0099 for this and it's only $10 plus shipping from Rock Auto.
I've had one of these in my 1990 for about 2 years and it's been fine.
Here's the page where you can see it listed as one of the coolant temp sensors for 1990 turbo. This list is a hodge podge of the 2 coolant sensors, but pick the "More Info" button for the NTK EF0099 and it will show you some pics and shows MD069879 as an interchange number.
If the NTK were no longer available I would probably try the WVE sensor. WVE is Wells Vehicle Electronics which always was a pretty good company and is now owned (since 2015) by NGK (Niterra).
NTK EF0099

Here's a link direct to the "More Info" page:
NTK EF0099 More Info

The temps I log with this sensor seem right on.
For example today was the coldest day I've ever driven my Talon with the new engine. Low temp last night was in the low 30's. Ambient temp outside was 41 deg F when I started my car at 2pm. Log shows 38 deg coolant temp at startup in the garage. Just right I'd say.
During the drive, temp came up to 183 degrees pretty fast as it should (180 degree thermostat). After that the temp was back and forth between 180 and 190 degrees, back and forth several times, for the drive of 2,140 seconds. Lots of up and down elevation and variable speeds. So that 180 to 190 is just what you'd expect with the chilly outside air and 180 deg thermostat.

Thanks, Rockauto has a lot of options, I generally forget them because they don't really have a customer service department, but at $12 its not a big deal if you eat a mistake.

The Walker Products sensor looking interesting, it shows 2 wires off the plug in connector which possibly could eliminate the pulling on the male spades issue.

Yeah Walker Products is another legitimate sensor company, so that one might be worth a try. It comes with a pipe bushing? The connector, the lock-on is right out there obvious where you can see it. That is a bad point about the Mitsu connector which does have a lock release button but it's hard to see when it's all dirty and full of gunk. I imagine a lot of people never see it and just pull real hard until something breaks. And if you aren't the original owner of the car it might already be broken - PO syndrome.

I've had OK experience with Rock Auto customer service. Have only needed it twice.
Once was last year, Gates 3/8" fuel hose came in a little clam shell that the hose had to be kinked over to fit inside of. Hard crease kink. I didn't like that so I asked to return. They gave me a refund and said I didn't need to return it.
The other time was just an inquiry - I wanted to know how to tell whether an item is in stock or not. They said if it's not in stock it will say so right on the look-up. If it doesn't say "Out of stock" or something similar, then it is in stock.
My only gripe about them really is that if you are buying several items and they don't all come from the same warehouse, then there is a shipping charge from each warehouse, and that can get pretty expensive. You have to look at that at checkout.

Duracrap is 2 degrees within the factory sensor, factory sensor would read on the Scanmaster 196 then the fan turn on (sensor in radiator), new sensor reads 194 then fans turned on so I'll keep this in mind.

I do like the Walker plug end connector better but I needed the car so I installed it today.

If curious, it needed over 30 ounces of empty bottle to hold the Coolant when I pulled the sensor. Also I made the error of filing the housing until it was full and of course that overflowed a ton before the thermo opened so I'd probably only fill back about 12 ounces then wait and fill the rest after thermo opened. If you fill to the top you'll want to close the cap, then after you see the readings drop from thermo opening you'll have to fill it hours later to cool down after shut off, restart and watch it flow and fill to the top then, my badd. Did this like a newb and made a mess.

I went with a echlin sensor from napa. I didnt want vatozone or oreilly napa had it in stock for $38 in california.

TX32 Standard Motor Products is one I have used. They are made at the factory in our city. Seem to work as expected, no NO STARTS at least.

Evil, is the sensor above the one you bought?
Because of that dudes bad review online I didn't want to buy it but normally I do buy Napa parts.

TX32 standard, great price, good to know another sensor is available and functions.

Car Cannibal said:

https://www.napaonline.com/en/p/ECHTS5552

Evil, is the sensor above the one you bought?
Because of that dudes bad review online I didn't want to buy it but normally I do buy Napa parts.

TX32 standard, great price, good to know another sensor is available and functions.

Click to expand...

Yes sir i saw that single bad review but it was for a vr4. It fit perfect on my 1g. Current data is good as well. I replaced it because i saw a spike to 300+ during cranking.

evil_eagletalon said:

Yes sir i saw that single bad review but it was for a vr4. It fit perfect on my 1g. Current data is good as well. I replaced it because i saw a spike to 300+ during cranking.

Click to expand...

Thanks for that input. I looked at that Galant customer review too, thinking it was strange.
NAPA should probably give the OEM part number that they think their part number interchanges with. That would help a little.
This part we are talking about, OEM part number MD069879, is used on a ton of vehicles. So it's no wonder that it is made or at least sold by several aftermarket suppliers.
The Vehicle Fitment list shown by Mitsubishi Parts Now shows 62 Fitments:

Hey all, what kinds of symptoms were you seeing on your DSM before you replaced the bad temp sensor? I've been getting rough idling when the engine warms up, hard starts, a gas/exhaust smell and poor gas mileage.

How is your O2 sensor? Do you trust it? I can't remember if you are running ECMLink or not. If so, watch it and your AFR gauge (if you have a wideband sensor). Maybe it is just way too rich.

1990TSIAWDTALON said:

How is your O2 sensor? Do you trust it? I can't remember if you are running ECMLink or not. If so, watch it and your AFR gauge (if you have a wideband sensor). Maybe it is just way too rich.

Click to expand...

Haven't gotten around to messing with the ECU and in any case I replaced my ECU years ago and the new one doesn't have a compatible EPROM.

But, I replaced the O2 sensor last fall when I overhauled the entire intake & exhaust, as the old one was definitely bad. I assume the new one is still ok and tested it when I installed it back then. I'll test it again but based on what I'm reading it looks like it may well be due to a bad temp sensor. I'll test it today to confirm, when it stops raining.