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Hello All,


I'm new to the forum, here's the information:


1996 Subaru Legacy (300,000 miles).


Over heated yesterday- on the "H", check engine light on, go to Autozone, code reads P0125, list "coolant temp is always low" then list probable cause "661-check coolant level"- checked, fine "662=Thermostat defective"- replacted thermostat, then boiled old one and it popped open, so it was never in need of replacement then "663= ECT (engine coolant temparature) sensor defective"- I don't even know what this is did nothing with it.


Then today, I had to pick my son up from school (single/astrologer mom who lives on student loans and near nothing pay), car makes it to school (no over heating), when we leave school car overheats, all the way to H- then car dies in street (hear what sounds like loud knocking 5 seconds before it dies). Car restarts, I pull over, wait for it to cool, then I drive home (3 miles) on "H" almost instantly.


Now it's parked outside, I have 0 support system and need this car to continue living if possible.


I burbed the radiator/bled it, check out the oil it is NOT milky, no white smoke out of exhaust, no bubbles in resevioure, no black much in there either (though some brown muck that's been in there since I bought it 3 years ago), looked at outside of head gasket and around- no coolant, no visible signs.


Is it the head gasket? The heater worked briefly on the ride to school (after I changed the fully functioning thermostat and flushed/bled radiator), then nothing but cold air the rest of the time. I know NOTHING about head gaskets other then the basic signs none of which I see though the car is in "H", the car DIED, and the heat is not blowing.


Please, someone, anyone, help me. I truly need an angel right now.


Also, as a side note I'm an astrologer and write weekly horoscopes, find me on FB or google Mystic Gwen.




The pic below is me and what I hope to be doing after one of you Yoda's guide me and that is smoking a CIGAR.


For the love of God, Alah, Buddha, Hendrix and Geddy Lee- HELP ME.


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The team here is the best around, so we'll get you going again.  For the gang, a little more info, please.  


Is your car a Legacy Outback or a regular Legacy (Brighton, L, LS, LSi)?  Or, what engine do you have in it? EJ22 or EJ25?  The front of the EJ22 looks like this (single circular spot on each timing belt cover on left and right side):


Or does it look like the EJ25 (two circular spots on either side of the left and right timing belt covers):


This will help people troubleshoot possible problems.


For the new thermostat, what brand did you get and install?  Was it a Subaru OEM t-stat or was it some other parts store brand?  Difference in shape size is this:


Non-OEM t-stats usually don't work well.


Was the coolant low at all when you checked it?  Are you cooling fans working?  Was the overheating happening while you were idling/standing still and/or while driving?

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Thanks you 2!


It's a Legacy L, it's got an EJ22 in it. It was aftermarket(murray), but the thermostat I pulled was too and in addition to that the one I pulled turned out to not be broken (I boiled it after the fact on the stove popped open and shut close on the counter). The Coolant resevoir was full, the radiator was pretty close to full, the cooling fans are working. The overheating happens, idling, standing still and while driving. So, there's hope still even though it died in the street on "H" and then re-started and was driven home on "H"? Thanks for the answers, I'm so worried.

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... "663= ECT (engine coolant temparature) sensor defective"- I don't even know what this is did nothing with it...


This issue Could being caused due to a Bad Temperature Sensor.


With engine cold, measure the resistance (ohms or  Value) of that sensor, to be sure it is according to specs, otherwise, change it; it could be sending wrong readings.


Kind Regards.

Edited by Loyale 2.7 Turbo
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There's still hope it may be ok, stop driving it or the heads are gonna warp. Or you could just end up with a scrap motor.


Any pressure in radiator hoses?

You said the thermostat you pulled was aftermarket?

I'd replace that with an OEM one and see what happens

Edited by TKFlight
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If it gets to this point, the temp sensor size and location can be seen here.  Not sure if you have a multimeter for measuring resistance/voltage, but if you do and you can dig into the temp sensor, resistance values are discussed in this thread.  A new temp sensor can be purchased at a place like Advance Auto for about $23 and they often have coupons (~30% off) you can find via a search on Google.  

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If it over heats again, open the hood, and look inside the over flow  radiator reservoir. Let the motor cool down some, then start the car. Look for bubbles flowing to the surface of the coolant in the reservoir. If you see bubbles, it is a good indicator that you have bad head gaskets. The bubbles indicate that exhaust gas is leaking across a bad head gasket and entering the exhaust system. This causes air to build up in the cooling system to prevent antifreeze coolant to flow through the system, so the engine over heats. It is also the cause of why there is no heat coming from the heater.


Look for bubbles.........let us know.

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1.  refill and make sure it's burped - get all the air out of the system.  any air in the system will make it not flow properly and overheat immediately - which yours is doing. 

2.  check for leaks - might be tough with the way everything spews on an overheat.

3.  clogged radiator....not sure how to diagnose that....the only time i had a bad radiator i ran a hose in one side of the radiator and visiaully look at the flow out the other side....it was noticably stifled by flow.  i wouldn't expect it to overheat so quickly unless it's just slammed clogged up.

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are you filling your radiator only? when I drain or burp my coolant I first fill up the radiator almost full then I fill from the bleeder valve on top or the upper radiator hose flowing into the engine. to fill both the block and the radiator, if your block is empty the fluid wont flow around properly and you will overheat. if your heater core has emptied it will cause a huge air pocket you must bleed off by running the heat on high fans on full for a long time! if large enough it can even cause the car to overheat. if you have a slight leak in your heater core it can allow air in (subaru coolant conditioner work well for fixing this) CHECK ALL your hoses there is one in particular that goes un-checked! just above the thermostat there is a small hose that leads up to your heater core to supply hot coolant, this hose can degrade and just slightly leak my leak was so small that it would dry before I could get down there to look at it.


any coolant seepage is bad and must be addressed even on a new hose, tighten it little bit by little bit untill no seepage can be detected. as well as any crusty build up around hoses indicate slow leaks that need to be addressed, all leaks will cause air to enter the system thus overheating your car.


REPLACE your coolent every 2 years its properties degrade then it will allow boiling at lower temps 

Edited by bluedotsnow
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