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Subaru Outback overheating but not overheating

I have a 2008 Subaru Outback that is telling me that it is overheating, the gauge is showing me that the engine is as hot as it could possibly get. However, its not actually overheating. It happened after a 15 hour day of driving from Cali to Colorado on 2 lane highways. In the morning it took 6 tries to get started, just sounded like maybe there wasn’t enough gas or something to get it going and if I fluttered the gas pedal the car threatened to quit on me. Since that moment the temperature gauge has been stuck on high, the check engine light is on, the cruise control is disabled and flashing on the dash, and the AC doesn’t work. I have turned the car off several times since the incident and it starts up just fine so far but the gauge and lights are still on. … Anyone have any experiences like this?

Take it to any auto parts store and the will read the codes for you…most of the time for free.

Then post them here and we will try to figure out your problem.


Is your battery original? Are the battery terminals clean and tight? Low battery voltage and bad connections cause problems like this.

My first suspect is you have a ground problem causing this trouble. Along with cleaning the battery connections (one of the biggest and easiest issues to fix that folks have) run a test ground lead from the minus battery post to a good ground point on the car chassis and see if that changes things. If it does then clean the chassis ground connections under the hood. If that doesn’t make any change try running the jumper from the battery to the engine block and see if that does anything.

If the test jumper makes no changes to the trouble then disconnect the wiring on the back side of the alternator, then start the engine and see if that makes any change. If it does then replace the alternator. It has some blown diodes inside it and they are causing excessive AC ripple voltage on the charging system.

Hopefully doing one of those things sheds some light on the trouble but if not let us know and we will try some other things. We may need to do some voltage checks if further testing is needed so hopefully you have a voltmeter on hand and know how to use it.

And no one suspects the ETCS (engine coolant temperature sensor)? That’s where I would start looking. The difficulty starting and running when cold is a sure clue, the computer thinks the engine is warmed up so it doesn’t deliver enough gas. Possibly the ETCS connector came loose or got some corrosion in it or the wiring harness got shorted.

I think the OP stated that the dash temperature gauge is having trouble, which uses a different sensor than the one used for the engine, unless things have changed from earlier models. I also assume the other things he mentioned started having trouble at the same time which makes me think the trouble isn’t just due to a sensor issue.