Coolant Temp Sensor

Sean486 · #1 08-26-2009, 08:26 AM

I just checked my codes and see that I am displaying a Code 21 Coolant Temp Sensor. I did a few searches and learned that it is located on the rear of the engine and not too expensive.
I was hoping that someone could just let me know how difficult it is to change that. I'm pretty inexperienced but if it is something that I can get at easily I'll give it a shot.

Hocrest · #2 08-26-2009, 08:34 AM

Not too bad, the only thing you need to remove to get access is the plastic H-6 Cover.

Standing on the drivers side, look under the the rear of the intake manifold, you'll see two sensors going into the coolant crossover.One sensor has one wire, that feeds the coolant temp gauge. The other has two wires, this one feeds the ECU, this is the one you want to change. to replace it, just unplug the connector and you'll need a deep socket (iirc 19mm or 3/4") to turn it out.

Make sure the car is cold, if it's hot the results when removing the sensor would be similiar to removing a rad cap on a hot engine.

SoCal LS-L · #3 08-26-2009, 11:42 AM

Yarp, it is eeeeeeeeeee zeeeeee. I would recommend (if you have a multimeter) testing the new sensor to make sure the ohms reading is within range. Some here have had problems with "new" sensors being total garbage.

At 68F room temp, the ohms should be between 2000-3000, if its a little warmer the reading will be slightly lower maybe in the high 1000's.

Almost forgot...check the harness too, the wire bends over 90 degrees from the main harness and sometimes the insulation will crack and short the wires, or the plug itself is dirty.

Sean486 · #4 08-26-2009, 03:48 PM

Thanks, I'll take a look at it tonight.

Sean486 · #5 08-26-2009, 08:29 PM

So is this the kind of thing that I can get at a parts store or should I go OEM at the local dealer?

SoCal LS-L · #6 08-26-2009, 08:49 PM

I got mine from Autozone for $26, works just fine. Not sure what the dealer charges.

SoCal LS-L · #7 09-11-2009, 09:52 PM

This seemed the best thread to ask a particular Q about my own CTS.

First off, the car has idled low for a long time now, I cant recall it ever idling normal (600), it usually goes to about 400 or 350 ish normally when im stopped, and the car is fully warm. Tonight was an exception.... heres how it went:

I took a cruise up the pacific coast highway for about 30 minutes.... car ran fine as always. Near home, I stopped at Mickey D's for sum food (barely). While sitting in the drive-thru, I noticed my car was idling higher, right at the line under the 1000 rpm mark (600-700?).
When I got home and parked it, I kept it running and the idle stayed stable at that top line, I thought maybe something cleared out of my IAC or something. I noticed my fans were going too. After about 1 minute of idling, the RPMs finally drop back to their normal low mark around 400. Crap.
So I sit there and wait, just out of curiosity, too make sure my fans kick off after the engine cooled down a little. Waiting. Waiting. After 10 minutes, theyre still on. I run the heater full blast for a few minutes, to where the air coming through the radiator is actually getting barely warm.... fans stay on. They didnt kick off until I shut the car off! I made sure the CTS was connected, checked for a CTS code, nothing.

The fans usually kick on and off just like normal, but for some reason tonight was special. Somehow im suspectiing maybe my CTS is giving too low a resistance reading to the ECU for the actual temp..... or its "sticking"? (I dont know how thats possible on a resistance type sensor).

Even when the fans kick on and off like normal, my idle has always been low.... but after my nice little drive something caused my car to idle normal.... and I liked it.

So the million dollar question is: Will an SVX ECU detecting an engine to be too hot cause it to idle low, even if it seems to properly kick the fans off and on (before tonight)?

svxfiles · #8 09-12-2009, 08:36 AM

Quote:

Originally Posted by SoCal LS-L

I got mine from Autozone for $26, works just fine. Not sure what the dealer charges.

22630AA041 Temperature Sensor $28.73 List
Subaruparts.com, plus shipping.$21.89

TomsSVX · #9 09-12-2009, 08:53 AM

Quote:

Originally Posted by SoCal LS-L

This seemed the best thread to ask a particular Q about my own CTS.

First off, the car has idled low for a long time now, I cant recall it ever idling normal (600), it usually goes to about 400 or 350 ish normally when im stopped, and the car is fully warm. Tonight was an exception.... heres how it went:

I took a cruise up the pacific coast highway for about 30 minutes.... car ran fine as always. Near home, I stopped at Mickey D's for sum food (barely). While sitting in the drive-thru, I noticed my car was idling higher, right at the line under the 1000 rpm mark (600-700?).
When I got home and parked it, I kept it running and the idle stayed stable at that top line, I thought maybe something cleared out of my IAC or something. I noticed my fans were going too. After about 1 minute of idling, the RPMs finally drop back to their normal low mark around 400. Crap.
So I sit there and wait, just out of curiosity, too make sure my fans kick off after the engine cooled down a little. Waiting. Waiting. After 10 minutes, theyre still on. I run the heater full blast for a few minutes, to where the air coming through the radiator is actually getting barely warm.... fans stay on. They didnt kick off until I shut the car off! I made sure the CTS was connected, checked for a CTS code, nothing.

The fans usually kick on and off just like normal, but for some reason tonight was special. Somehow im suspectiing maybe my CTS is giving too low a resistance reading to the ECU for the actual temp..... or its "sticking"? (I dont know how thats possible on a resistance type sensor).

Even when the fans kick on and off like normal, my idle has always been low.... but after my nice little drive something caused my car to idle normal.... and I liked it.

So the million dollar question is: Will an SVX ECU detecting an engine to be too hot cause it to idle low, even if it seems to properly kick the fans off and on (before tonight)?

In so many words, no. If the engine is too hot it will run the fans and raise the idle (more or less to compensate for the load of the fans on the alt.) Have you checked your TPS voltage? A low TPS adjustment can cause a low idle

Tom

SoCal LS-L · #10 09-12-2009, 09:57 AM

Quote:

Originally Posted by TomsSVX

In so many words, no. If the engine is too hot it will run the fans and raise the idle (more or less to compensate for the load of the fans on the alt.) Have you checked your TPS voltage? A low TPS adjustment can cause a low idle

Tom

Ah yes I did a few months ago and it was a perfect .5v. I have been chasing this little problem for too long, I suspect that I wont be able to nail it until I remove my intake manifold to clear out the rest of my EGR passage. At that point, I can check the other vacuum hard-lines for clogs (like the prior EGR vac line), and maybe clean out the IAC valve?

One thing of note, im not sure if this is normal/common or what. When I feather the throttle, I hear a click and then air being sucked as the RPM's increase. I let off the throttle, the RPMs return to idle and right after they do, about 1 second after, the click is heard again and the air suction sound stops. I assume solenoid, but for which system?

trophy956 · #11 09-12-2009, 07:38 PM

hi code 21 id replace the temp sensor, oem ive never had a problem with a subaru sensor at 28 i wouldnt by a knock off

SoCal LS-L · #12 09-13-2009, 06:01 PM

Nobody has the same suction noise?

TomsSVX · #13 09-13-2009, 07:32 PM

Is that because the EGR control solenoid is opening and the line on the other side of the solenoid is broken or dismounted? I am sure you know when the EGR valve is supposed to open/close. Sounds like you are hearing the clicking and suction noise when it is supposed to operate. now with all the codes you have for your EGR don't you think it might be correlated??

Tom

SoCal LS-L · #14 09-13-2009, 09:07 PM

Quote:

Originally Posted by TomsSVX

Is that because the EGR control solenoid is opening and the line on the other side of the solenoid is broken or dismounted? I am sure you know when the EGR valve is supposed to open/close. Sounds like you are hearing the clicking and suction noise when it is supposed to operate. now with all the codes you have for your EGR don't you think it might be correlated??

Tom

If you mean the vacuum lines those have been checked and rechecked, makes sense it would be the EGR gasses porting into the manifold making the sound though.

Heres an even bigger question..... I just went out there with a flashlight and mechanics mirror, and my ears. All hoses connected, but:

The sucking sound starts right in the middle of the manifold right by the IRIS valve. A split second later the sound moves to the passenger side of the manifold, and stays there at any RPM besides idle. At the same time as the sucking sound starts, the click, it is felt in the fuel line to and from the fuel filter!! The click coincides with a fuel pulse, and the fuel pulse coincides with the start of the sucking sound, which instantly moves from the middle of the manifold to the pass. side

Is my car just special, I mean can anybody here say that their car has the same sucking sound under the manifold with the throttle anywhere but idle? Im lost

LetItSnow · #15 09-13-2009, 09:54 PM

Regarding the hoses, connected is connected, but have you checked their condition? With the engine I just picked up, the hose leading to the IRIS from its actuator solenoid valve had been worn away in a choppy fashion on the bottom, right in the middle. It hadn't gotten to leaking, but it was sure in bad repair.