Malfunctioning temperature gauge needle.

[Rognmoe]

Hi, all!

Had something odd happen last night. As I was driving home, I noticed my engine temperature gauge needle wasn't registering temperature in the engine.

This morning, the gauge was working again, but 3/4 the way to work, I noticed the gauge was down again AND my check engine light was on. I pulled off and checked under my good to see if I was losing coolant, but I wasn't.

I turned the car back on and the gauge worked again and I drove it to work without a problem. The gauge worked fine most of the way home, too, but I was keeping an eye on it the whole time. I actually watched the needle drop, like they do when you turn the Night Panel on, but it was just the temperature gauge.

Is the needle attached at all to the thermostat? Could it be going out? Or is it more likely a bad connection making it switch off?

The CEL is kind of worrying, but the car isn't misfiring or misbehaving that I can tell. Weirdness.

Any insight? I'm going to take the car in, eventually, but being Christmas, the funds are pretty tight.

[Brad Lauzze]

Sounds like a thermostat to me, CEL is probably for ECT performance problem.

[Rognmoe]

ECT performance problem?

[Brad Lauzze]

Engine coolant temp sensor performance problem. Can't remember the actual code number.

[Rognmoe]

Read a post on Saablink, describing my EXACT problem, and they say its the coolant temperature sensor, since it was accompanied by a CEL.

Guess I'll replace the t-stat, anyway, since they're only $18. Tutorials, here I come...

[Brad Lauzze]

T-stats are very easy to do on these cars. Just follow the instructions and take your time and you'll have no issues.

[nordwulf]

It will probably be a P0116 code. I would call replacing the thermostat 'challenging', even though it got easier after the third time time I did this.

http://saabworld.net/f9/engine-temp-...sor-p0116-920/
http://saabworld.net/f29/saab-9-5-th...e-engine-1019/

[Yamarocket630]

Read a post on Saablink, describing my EXACT problem, and they say its the coolant temperature sensor, since it was accompanied by a CEL.

Guess I'll replace the t-stat, anyway, since they're only $18. Tutorials, here I come...

The ECT sensor is fine. Just replace the thermostat.

[Rognmoe]

The ECT sensor is fine. Just replace the thermostat.

Why do you say that? The people were pretty specific that if the CEL comes on, it's the sensor.

[Yamarocket630]

I've seen plenty of sensors replaced for p0116. It always comes back. It's never the sensor. The logic for p0116 is not for a defective sensor, its for the engine taking too long to warm up. The thermostat is opening too soon causing the engine coolant to be colder than expected.