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Subaru Outback 2001 VDC problem

My Outback is a fabulous car, but has developed a mysterious problem a few years ago. When it was very hot outside and I was driving uphill (happens a lot in the mountains), the VDC warning light would come on and the temp gauge would begin to rise. I’d turn off the AC, and eventually the light would go off and the temp would return to normal. Now it happens a lot in the summer. I can be idling for 5 minutes or so with the AC on, and the light will come on, etc. etc. I also can be driving up a steep mountain (again, on a warm day) without the AC and the light will come on and the heat gauge will rise. One mechanic told me that modern cars almost never overheat so not to freak out; and it’s true, when the gauge gets to the red zone the car itself does not seem to be hot. We replaced the thermostat, flushed the radiator, searched forums, nothing affected it. I took it to the dealer. They said it was caused by the “steering angle
sensor”, a repair of $800. That made little sense to me, so I took it to another highly-rated mechanic who searched forums who found others having the same problem, got the same message from the dealer, and an average of $2500 later - those others having replaced all sorts of expensive computer parts - were still having this mysterious problem. Can anyone make sense of this? Do I just need to buy a new car?

Just a warning from the somewhat wise, if you want some real trouble just let that motor overheat. Then you really will want to dump the car. Soob engines do not suffer well from overheating problems. So never ignore that engine temperature gauge. You will have head gasket problems if you let it get away from you. As a fellow Soob owner that’s all I’ve got to say about that.

It might help to replace the radiator if it has some scale buildup on the inside of it. Sometimes just flushing doesn’t do the job that is really needed. I assume the cooling fans are working correctly and turning on when they should be. I’m not sure why the steering angle sensor would be related to a engine temperature issue. I also haven’t heard of that before this.

Here is a very basic question that may relate to the issue:

Are you using premium gas, as is specified for the six-cylinder engine in this car?
If the answer is, “no”, then that is the first thing to try.

Although that engine will run “acceptably” on regular gas most of the time, it will not run well when the engine is stressed, such as during mountain driving. The design of that engine is such that the cooling system passages for the rear two cylinders are slightly smaller than the other 4, and that can lead to higher than normal temps in those cylinders when the engine is stressed. That reality led to the specification of premium gas for that engine.

Unfortunately, some well-meaning folks will tell you that it is okay to use regular gas in an engine that calls for premium gas, and this is one example of why they are not always correct. Trust me–using lower-octane gas can lead to overheating of this engine.

As to the VDC light coming on along with the rise in engine temperature, I have no explanation for that. It could be coincidental, or it is possible that high temps in the engine compartment are leading to electronic issues with the VDC system’s sensors and circuitry.

Edited to add:
I just thought of a direct connection between the overheating and the VDC light.
When the car’s OBD system detects a problem such as pre-ignition or misfiring, it will disable the VDC system, and the traction control system, and the cruise control. So, if the engine is in distress from the overheating situation, I would not be at all surprised if the VDC light (as well as the Check Engine Light) was lit up. And, it is entirely possible that this is all the result of gas that is too low in octane.

I would suggest that you try my suggestion regarding premium gas before you do anything else, as it just may resolve both issues. Because I had the same car (albeit a 2002 model), I do have relevant experience with this model, and I strongly suggest that you NOT use regular gas in it.

I found this model to be rock-solid reliable–up through 120k miles, but I used only premium gas in it.

@VDCdriver, have you heard of a steering angle sensor before? That’s a new one for me.

If you are idling with AC on the fan should be coming on. There are 2 fans. One turned on by engine temp and 1 turned on by the AC. Make sure they are working. It could be the temp sensor or the fan relay or fan itself. If you are driving and going up a hill the stress will cause the engine to knock. This is why @VDCdriver is telling you to use premium gas. The timing will need to be checked and hopefully your timing belt has been replaced. If not it will stretch and that could be your issue.

@Cougar–Of course I have heard of a steering angle sensor!
The “VDC” that the OP referred to is Vehicle Dynamic Control, which is Subaru’s name for Vehicle Stability Control. Those systems all use a steering angle sensor, in addition to the wheel speed sensors, in order to determine if you are going into a skid, and in order to know which individual brakes to pulse so that it can pull you out of that skid.
(Edited to add: These systems also use yaw sensors)
And…I can tell you that all of this complexity works very well–if the engine is operating at its optimum, which the OP’s vehicle clearly is not.

@knfenimore–This model Subaru has a 6-cylinder engine, which utilizes a timing chain, rather than a timing belt. That is one of the reasons why I opted for the 3.0 VDC model when I bought my 2002 Outback.

Thanks for the info @VDCdriver. What you say makes sense. I am aware of the VDC system just not up on how it all works. When I purchased my LL Bean I opted not to spend the extra money needed for the VDC model.

There may be more than one problem here and there’s not enough info known to be able to make much of a guess, but I might question the shop’s abilities.

They state that modern cars almost never overheat, don’t freak out, and the gauge going into the red is not an issue?

That’s pretty poor advice IMO.

Thank you all very much for the input. I will print out these replies and take them to my mechanic so we can educate ourselves. (This is not the same mechanic who told me modern cars rarely overheat, by the way, though he has a 30-year shop with very experienced mechanics; I didn’t talk to the new guy at Grease Monkey, in other words. But I clearly need to understand cars better than I do.)

I will first try the premium gas advice, thank you VDC driver, because it is the simplest and makes sense. I’ve been using 87 octane, which at altitude is probably equivalent to about an 89. The highest octane rating we can get here is a 91. So that’s what’s going in my car tomorrow.

I just hit 170k on this vehicle, and aside from maintenance on the kinds of things that get beat up in the mountains, it’s been a trouble-free car with great performance.

“I didn’t talk to the new guy at Grease Monkey”

If the Grease Monkey places in Colorado are like the ones on the East coast, they are quick lube places, and do not have actual mechanics on staff. These people are not knowledgeable enough to be able to diagnose engine problems, and probably don’t even have the proper tools or equipment for anything more complex than fluid changes.

So, if you are relying on somebody at a quick lube place to know how to maintain (or–God forbid–to repair) your car, you are making a MAJOR mistake. Personally, I wouldn’t even trust the people at a quick lube place to change my oil without damaging the car.

Please–for the sake of your wallet, and for the sake of your car–find a real mechanic and do not take the car to a quick lube place. If you use the Mechanics Files button at the top of this page, you should be able to find a few competent mechanics in or near your zip code.

If your temp gauge rises and then the VDC light comes on it likely is due to a code thrown not your VDC in failure. I would suggest concentrating on the overheat issue first and ignore the VDC issue for the moment. You may find the VDC pest disappears once overheat happens.

VDC off is not the end of the world it simply means your stability control (not avail on all other Subie’s at time) is not working.

I agree with OK4450, but with more emphasis. That is EXTREMELY bad advice. And also incorrect. Modern cars DO overheat, but when they do it’s because of a problem. Many moons ago, perhaps 40 years and more, overheating was not uncommon and if you go back far enough it was not necessarily indicative of a specific problem. But that was then. In a modern car, if your temp gage is pushing the limit, you have a problrm, and if you don;t get it resolved it will come back to bite you.

There are numerous diagnostic tests that can be done to find the cause of a chronically hot engine, including but not limited to heat mapping of the radiator, flow testing of the radiator, testing ot the thermostat, testing and examination (for impellar wear) of the water pump, and checking for headgasket uintegrity (via a pressure leaksdwon test). Include also pressure testing of the system, UV dye testing if there is a leak, and testing of the radiator cap.

This is a change of performance in the engine. Consider it a warning sign. Find a good shop with the diagnostic knowledge to persue it. I agree with Andrew and others that the VDC light is irrelevant to the heating problem. The VDC light will not cause other damage. The high heati levels will. Ignore the VDC light fofr now until you get the high heat problem solved.

Sincere best.

@VDC Driver – sorry for the mechanic confusion, I was making a poor joke about the fact that I did not consult a brand-new mechanic at Grease Monkey, but rather guys with decades of experience. Out of curiosity I looked at the mechanics files, and saw that the mechanic who told me not to freak out about the rising heat gauge is the owner of a five-star shop. My current mechanic is also a five-star rated mechanic. I took the car to another shop here (4 stars) that only works on Subarus, but I didn’t care for them as I had problems after one of their repairs.

And to clarify, since this problem only happens in the summer I am not worried about the VDC going off. The VDC has been very helpful on gravel roads – but going downhill, when the car may slip, and the VDC/overheat problem happens uphill.

So, I put premium gas in the car. There were probably 2 gallons of the lower octane still in the tank. Today the light came on on a steep hill - though it did go off fairly quickly. I am hoping that after I replace one more tank of gas I’ll have a better sense if the pattern is shifting. Thanks, everyone, for all your advice.

I was experiencing the same problem. It turned out the Main fan on the drivers side of the car,
needed to be replaced. Did the job and problem solved!

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