2008 - Temp gauge in the cluster - sensor location? - Updated!

8227 Views 38 Replies 6 Participants Last post by 2.5x_sleeper, 15 d ago

Goose929

Discussion Starter · Jan 10, 2019

All, I apologies if this is a repeat but hear me out. I have an 08 Subaru Forester X that I just bought. The temp gauge in the cluster does not work. I know the fans work though because they will go on while the car is running and keep the engine from running hot. The local dealer here said that there was only one sensor for the car and it was on the crossover pipe but does both. That sensor does the gauge and the fan for the engine. So I replaced it and nothing. Fans still go off when needed and the gauge has no movement. So I have searched the internet and tons of people say there are two sensors for the cluster and gauge. BUT NO ONE SAYS WHERE IT IS!!? So I need help.

I don't know if there is truly two sensors on the car or if my cluster has gone bad. You would think that if the cluster is bad, I would have more than just that gauge not working. Well, everything works on the cluster so I am inclined to think that there has to be a wire somewhere, that goes somewhere on the engine that tells the temp of the vehicle. I don't want to change out the cluster and find out it is still not working so I am reaching out to all of you first to see if you can help. I know there is a small sensor next to the one on the crossover pipe I just changed (just off the pipe and closer to the front of the car by about 3 inches but same wiring bundle) but I don't know what it does. It only has one wire coming to it and the dealer does not show it on the expanded view parts. Could this be it? Is there a part number I should be looking at? I really don't want to take it to the dealer as I am sure they are easy fixes and I can usually do a lot of work if I know what it is.
I have called 3 Subaru repair places. One said there is a sensor for the gauge but can't tell me where, just wants me to bring the car in. The other said the car only has one sensor so they need to see it and the third said it was the cluster and should def be replaced before even seeing the car. Three different places, three different answers. ***Frustrating***

So fellow peeps, can anyone please lend a hand? Is there truly another sensor just for the temp gauge? Where is it and what is the part number?

Again, all the other posts talk about this but I cant find a picture of the location or any part numbers. Let alone a confirmation on a 2008 that it even has a temp gauge sending senor or what ever it is called.

Thank you all in advance!

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2.5x_sleeper

· #2 · Jan 10, 2019

Looking at the Subaru technical documents, there's one sensor. It's labeled "engine coolant temperature sensor and thermometer".

This is a 3 wire sensor. The engine coolant temperature sensor goes to the ECM & the thermometer goes to the coolant temperature gauge.

[1] to ground
[3] to the coolant temperature gauge
[2] to the ECM

Bobby...

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Goose929

Discussion Starter · #3 · Jan 10, 2019

Thank you Bobby.

The dealership sold me the sensor that had three prongs to change out which matched what the screen said for the year. When I got home, my sensor only had two wires, not three and the plastic plug in was not the one that matched my wiring. When I went back, they had a tech come out and he actually found the two wire sensor which plugged right in. He said some have that one.

It does not look like it has ever been changed out and still all factory. He said that some of the cars came with this two wire setup.

So could there be another sensor? Or how can I at least test the gauge in the instrument panel to see if that works?

Thank you

Goose929

Discussion Starter · #4 · Jan 10, 2019

I will try and post a picture here today that shows the setup I have. Maybe that will shed some light too.

Here is a pic of my sensor that only has the two wire setup and surrounding wires. Maybe this can help.

Auto part Automotive fuel system Fuel line

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Goose929

Discussion Starter · #5 · Jan 10, 2019

Bobby,

I should also point out it has the EJ25 engine it appears due to the stamp on the block. If I look up the sensor for that motor, I find the two plug version and not the common three plug that you mentioned. Could that make a difference and therefore have an additional sensor?

Curt

2.5x_sleeper

· #6 · Jan 10, 2019

Curious... looking on the Subaru technical service documents, '03-'05 & '06-'08, all show the same 3 wire sensor.

However... the later models changed to CAN bus, so it's possible the temperature readings are taken from what the ECM - engine control module receves, hence only a 2 wire sensor.

If you have access to a Scangauge II, UltraGauge or an OBD2 scan tool, you can verify the temerature sensor is functioning, as they will display the coolant temperature. We have a Scangauge II installed in both our Foresters.

You can view my write up here in my Member Journal: ScanGauge II is installed!

Bobby...

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Goose929

Discussion Starter · #7 · Jan 10, 2019

I don’t have any access to those unfortunately. I know the fans cycle on and off when the engine is sitting there running so I know it’s getting some kind of temp reading to turn them on. And the vehicle does not overheat either.

Goose929

Discussion Starter · #8 · Jan 15, 2019

Bobby,

So I found a friend that has the tool to read the ECM. We did it last night and the car is reading the current temp of the coolant. So we pulled the instrument cluster and he ran a test on gauge itself. Shows it had an open circuit so he is pretty sure the gauge itself is the issue. He was able to find just the fuel/temp gauge and looks like we can replace that peice alone and not the entire cluster. I hope that solves the issue!

Thanks for telling me about the scan tool! I would’ve been going in circles without it and never would’ve asked around! I’ll keep you posted after I order and install the new gauge.

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2.5x_sleeper

· #9 · Jan 15, 2019

Thank you for updating your thread! I'll add "Updated" to your thread title. 😉

Bobby...
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Goose929

Discussion Starter · #10 · Feb 6, 2019

So a little update. I got a new temp gauge and we installed in in the old cluster. Very easy install. Unfortunately, that did not fix the issue. The fuel gauge works fine but still no temp working. We are going to start to trace wires from the cluster back. It’s possible it’s the board on the back of the cluster and could be a wire. Hope to god it’s nothing in the computer though. So still no luck but will keep plugging away!

Minikiller

· #11 · Dec 7, 2020

I know it has been a year since you last posted on this problem but could you give a final outcome? Were you able to figure out the problem?

2.5x_sleeper

· #12 · Dec 7, 2020

@Minikiller note that @Goose929 last signed onto the forum over a year ago. You could send the member a PM - Private Message... now called a "conversation" on this new site. The member is optioned to receive an e-mail notification, so you could receive a reply to your question.

Bobby...

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Minikiller

· #13 · Dec 7, 2020

No worries, Thanks 2.5x_sleeper. I will get my details in place also. 👍

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2.5x_sleeper

· #14 · Dec 7, 2020

@Minikiller what specific issue are you troubleshooting?

Bobby...

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Minikiller

· #15 · Dec 7, 2020

We swapped a JDM 2.5 n/a into my son's 2006 X and the only issue we have is the coolant sensor on the original motor had the 3 wire sensor and the JDM has the 2 wire. Just trying to figure out if the 3rd wire is only going to the gauge or is routed to the ECU then to the gauge?
Trying to find a wire diagram of the main engine connector is a nightmare. I'm willing to run a separate wire to the corresponding on the other side of the connector if I have to. Just was trying to avoid having to remove the intake and everything to swap the whole harness for the one connector....

2.5x_sleeper

· #16 · Dec 7, 2020

@Minikiller the snippet below is from the Subaru technical documents, for the USDM '06-'08 NA - naturally aspirated engine.

What I see... my guess of course:
[3] Sensor for the combination meter coolant temperature gauge.
[2] Coolant temperature sensor for the ECM - Engine Control Module.
[1] This wire connects to numerous sensors, all connected to the ECM. Could be a +12V or -12V, ground supply? I'm leaning towards +12V, but you'd have to verify... check with a meter.

► Disclaimer - always verify any information you read on the internet, especially if you're going to spend money on parts!

Bobby...

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Minikiller

· #17 · Dec 7, 2020

Dang I looked at a million different diagrams and never saw this one. It does answer my question regarding the 3rd wire and I will confirm it with a scan tool on Wednesday. It also gives me the pin 11 on the wiring connector that I can confirm is missing when I get home. Thanks for your help Bobby it is much appreciated!

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2.5x_sleeper

· #18 · Dec 8, 2020

@Minikiller as I noted, the diagram I posted is my "snippet"... pieces pulled from multiple document pages, so it can be viewed on one page! The engine electrical PDF has 30 pages, with links to numerous pages!

Bobby...

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Minikiller

· #19 · Dec 8, 2020

I sure appreciate it!!! it's a great reference for what I was looking for and answers a lot of questions that would have taken quite a bit of time to figure out.

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2.5x_sleeper

· #20 · Dec 8, 2020

@Minikiller it's curious that @Goose929 2008 X has a 2 wire coolant temperature sensor! No first hand... hands on experience on this, as there has been no need to work on the coolant sensor on either of our Foresters. The Subaru technical service documents for the '03-'04 & '06-'08 shows a "3" wire coolant temperature sensor?

Bobby...

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