01 9-5 3.0 another coolant temp sensor problem?

[roree]

Hi all,
I am fairly new to this site. I just got an '01 9-5 3.0 wagon. I love the car. Anyway, the hot water bypass valve sprung a leak. I replaced it with no problems except now, while I am driving the engine temperature gauge sometimes bottoms out. The A/C goes down and the engine light came on. If I turn off the car for 30 seconds and restart, all is fine. I can run it for 50 miles or 5 miles. No telling when it will happen again. Is it:
air in the system?
bad temp. sensor?
bad t'stat?
or something else. Thanks any help is greatly appreciated.

[seriks1]

temp sensor. Stops your a/c and runs the cooling fan as a precaution because the ecu doesn't know how hot the engine is

[BurnsSide42]

Also good idea to replace the t-stat and flush the cooling system (if you didn't when you replaced the heater by-pass valve) with the coolant temp sensor. Then you will be all set for several years - pending your hoses are intact and healthy.

[JustinHiFi]

Second the temp sensor. Saab pn15393755, about $17. Since you have the 3.0L, thermostat housing is a royal pita to get at and change. They are very simple to change when doing a timing belt job, so tend to replace thermostat and water pump assembly when thats all torn down. Its pn90502201, about $95.

[el-anders]

Like the SAAB experts here are saying, its probably the tempsensor.

But here is what happend to me when I first started a 3.0, after a headgasket and oilcooler job.

I thought I got out all the air in the coolant system, and it was running fine. The temp needle went up and up and then bottomed out. I checked the engine temp with an IR meter, and it was normal, so I let it sit for the night, while I went home and ordered a tempsensor online.

Come back in the morning, and the engine had "burped", so just to have something to do while waiting for the sensor, I filled it up with coolant and let it run a little.

Now the temp was perfect, so I let it run more. It turned out that because I didn't bleed it with the bleed plug close to the temp sensor, there was air in that "tube" between the 2 heads. When the air was gone all was good, and the car has been running soon a year with the old sensor.

So I have one sensor for sale....hehe.

[jssaab]

All wrong for a T7 car, Its the T-stat, If T7 senses that the temp is not going to operating temp ( too low) in the required amount of time, it drops the Temp gauge to zero, kinda as a visual its not up to temp indicator ( there is no light) Did you notice the temp not quite making it to the 9 o'clock position prior to this?, it woudl indicate a failing T-stat...

that said for the V6 if you are in there do them both its not worth the hassle of dong one then tearing it al down to do the other...

[NickTurbo900]

Originally Posted by jssaab

All wrong for a T7 car, Its the T-stat, If T7 senses that the temp is not going to operating temp ( too low) in the required amount of time, it drops the Temp gauge to zero, kinda as a visual its not up to temp indicator ( there is no light) Did you notice the temp not quite making it to the 9 o'clock position prior to this?, it woudl indicate a failing T-stat...

that said for the V6 if you are in there do them both its not worth the hassle of dong one then tearing it al down to do the other...

I disagree. I have replaced several temp sensors to solve this problem successfully.

I've had temp sensor's go in and out on a test drive, and the needle will jump between normal and none and cause a cel related to open circuit, coolant temp sensor. I have not yet seen a failed t stat cause a full low warning, only a 1/4 way up the gauge or too slow to reach normal (and a cel sometimes for failed to reach operating temp in allotted time.)

I don't know of any 'feature' that T7 uses to give an exaggerated low temp signal for a thermostat failing. Where did you find mention of this?

[saabrick]

What should it cost for t state, temp sensor replacement on 3.0?