Temperature Sensor?

[psa55]

Hi All,

I've got a quick question... my Engine Temperature gauge is working less than half the time. When it works, it seems to come up to a normal operating range... just less than 100 Celsius (or 212 F). Most of the time the engine temp now just sits at zero and never moves, regardless of how long I've driven in. It started last winter and has gotten progressively worse, and I had good heat last winter.

I'm assuming its as a result of a bad temperature sensor? And that the Thermostat is okay. Anyone have any other thoughts?

My AC seems to work intermittently lately as well, and I wondering if the two issues might be connected.

I've found this image from freddyboy61 to help locate it on my 2008 TB, with the I6 engine.

 

[shovenose]

if you tap the gauge cluster when gauge is not working does it pop up the right palce? it could be a problem with gauge cluster.

 

[dmanns67]

First I would take a scan tool or OBDII bluetooth scanner and see what your ECT sensor is seeing as far as coolant temp goes. Should be around 194*F at full operating temperature. If the ECT sensor is not seeing the correct coolant temp, then that should throw a CEL.

If you do not see any temperature reading from the ECT sensor with a scan tool then your sensor has failed. If you do see a reading then I would have to assume your temperature gauge stepper motor is failed/failing. If you are going to replace one stepper motor, I would suggest going ahead and replacing them all at the same time.

The ECT sensor changed position after 2005 on the I6. It is now in a PITA spot on the engine, passenger side near the firewall. The sensor was in a better location for replacement on the 2002-2005 I6 when it was located near the t-stat.

Start with seeing if the sensor is functioning and reading accurately before you start throwing parts at the issue. If the temp reading is good, you will also confirm that your t-stat is functioning as it should.

 

[psa55]

Thanks guys! I hadn't checked for a code as I get the P0446 regarding emissions off and on. I was just out, and the engine temp gauge worked this time and gave me a reading. At the same time, I ran a scan with the scan tool.

I got a P0128, related to a Coolant issue, and P0446 codes. Took a picture of the gauge temp working. Not sure I'm any further along with this info... maybe it indicates that it is just the gauge.

 

[Sparky]

If you got P0128 then you're looking at doing a thermostat, but that assumes the sensor is sending correct data. Obviously the PCM can't tell you accurate information with that if the sensor isn't feeding it good data.

 

[psa55]

I think I can live with that... I've got 215 000 kms on the TB and those parts are original....I usually prefer AC Delco products, but the part shop around the corner has a Gates Thermostat in stock and a Hygrade Coolant Temperature sensor. I don't know much about them. Anybody have any experience with Gates or Hygrade?

What is the easiest way to get at that Temp Sensor... I just checked it out and it is a PITA from above. Is there better access from underneath?


Thanks!

 

[dmanns67]

How is RockAuto.com shipping prices to Canada? I purchased both my t-stat and ECT sensor from their site and each part was under $20USD. I went with the Stant t-stat. I dont have much experience with either manufacturer that you listed.

I do not think there is enough clearance to reach the ECT sensor from underneath. Definitely not feasible by yourself laying in the driveway under the vehicle. Maybe with a car lift and two people. You will just need to lay across the engine bay. Having a few extensions and some u-joints will help with the reach.

You might have it already, but you will need a deep 18mm slotted socket to remove the sensor. Something similar to the pic below. You will likely need to buy a 18mm socket and slot it yourself as I was not able to find any for sale via Google. Only ones I was coming across were slotted 22mm sockets for O2 sensors.




**Also, I did not see you mention what temperature the ECT sensor was showing when you had your scan tool hooked up and vehicle was at operating temperature. You might not even need to worry about replacing the ECT sensor.

 

[Mooseman]

Check prices on Amazon.ca. Sometimes better than a lot of places ( I just ordered a MAF and oil pressure sender from there). I would also recommend that you stay with ACDelco. I had a Stant t-stat and it ran a little colder than the Delco. Also better to stay stock with sensors. Look up the part numbers on RockAuto and search for them on Amazon.ca.

If the sensor is good and you've been running at a low temp, your cat may be getting clogged and causing the poor performance, especially if it's getting progressively worse. Change the t-stat and check for backpressure in the exhaust.

 

[psa55]

Thermostat is in, gauge came right up and a better operating temp. Went with Genuine GM/Ac delco... Off all places, the dealership was by far the best price! Only $10 more than all the other brands.

My ODBII isn't a Bluetooth adapter, so I am going to pick one up to allow me to scan the coolant temp, among other things. I've read a fair bit about them the past few days.

I haven't really noticed a drop in performance, but I'll watch for it. And... I'll search some forums here to see if there is an easy way to check for back pressure. Thanks for all the help everyone!!

 

[fletch09]

instead of starting a new thread, i'll post here.
09 TB, 84 k mi last sat night noticed the check gauges light was on. temp was stuck at 100. had possibly driven like that for 30-45 min. did not notice any coolant on floor like it had over heated. drove it sun morn. same thing, but while driving, after about 15 min., light went off and temp came up to norm. ( just happened to be looking at it that exact time) everything fine until today. light on temp stuck @100. have not driven it as long as i did on sun. when it started working. the temp gauge will act like the others at start up. (move far left first, then to position) except temp gauge at this time. at first, not knowing there was an ECT sensor, thought t-stat sticking. now thinking and/or sensor.
being an older guy use to t-stat being on top of engine in front, i assume the t-stat assy is the part that is on the other end of the upper hose, opposite radiator. have yet to locate where sensor is. have looked at pic in 1st post, but being the coldest day of the year so far in Chicago area, may wait til i get in my garage to search further.
thoughts from the more knowledgeable than I ?

 

[Mooseman]

On 09, the sensor is on the passenger side of engine. T-stat is on driver side, below/behind alternator.

 

[fletch09]

thank you.
last night, light still on, still @100. let is sit idling 5-10 min while i ran in to pick up some food. when i got back in, light was gone and temp read normal. after sitting for 11 hrs. got in this am and everything back to normal. while temp gauge is stuck @ 100, i still have heat.

 

[Sparky]

Sounds like a sensor failure to me.

 

[fletch09]

that's what i was thinking. will get it checked out soon.