2006 S80 2.5t Reduced Performance Causes

WavyQuantum5569 · Post by **WavyQuantum5569** » 10 Dec 2025, 16:41

Hello everyone. I've been lurking this forum for a while as I have been trying to figure out what is ailing my 2006 AWD S80. So far I have come across a lot of good information so that I can at least try to know what I am talking about. My car has been stuck in limp mode and as a result it has not been on the road for a little over 2 years. The entire time I have been waffling about debating whether or not I want to try to fix things myself; I have been forced to act now because I am moving to an even colder area with more snow and I think I have decided to get this car back on the road as a daily driver.

In October of 2023 I drove the car 2 hours to a concert on a Friday evening, drove back 2 hours that same night, and parked it over the weekend. It drove perfectly normally just as it had since I had owned it. I did not have work that Monday, so the next time the car was started was the following Tuesday morning. Upon leaving for work, the car displayed a "reduced engine performance" error message along with a yellow triangle light. The car was idling normally so I started to drive to work; I turned around after about a block because of how little power the car was making. It was still idling okay and the engine was not making any strange noises. I parked it on the street so that I could pull my other car out of the garage to go to work. Later that evening I wanted to pull the S80 into the driveway again; it still had the message but I reversed out of the street, pulled up to the edge of my driveway, and found that the car seemed not to have enough power to pull up my slightly sloped driveway. I turned the car off at the bottom of the driveway, turned it back on, and was able to pull up to it's normal parking spot. A very similar set of events happened a few weeks later when I once again had to move the car out of the way to make room for other automobiles. In hindsight, I think that the car was simply not responding to the accelerator pedal input during those times I felt like it did not have enough power to pull up the driveway. I've gone to mess with the car several times over the last couple years and it's always had the limp mode engaged; even after swapping batteries and leaving the car without a battery for months at a time.

As I have been messing with it more recently and paying closer attention, I have noticed several times where the engine does not respond at all to pedal input. It happens maybe 1 in 5 starts. The car is absolutely limiting itself on power, but it was able to pull itself onto some ramps for an oil change a couple weeks ago. The lack of pedal response is always fixed by a restart. It does not pull the car out of limp mode, but does allow me to move it around the driveway and street. The research I have done leads me to believe either the accelerator pedal position sensor or the electronic throttle body is giving me issues. I am making this post to see if any of you can confirm or provide any input since I am a novice mechanic. The car has about 150k miles and is in good condition. It still starts right up and idles really well. There don't seem to be any odd noises. When I apply the limited throttle I get, I hear some turbo whooshes so I don't think that is siezed. Are there any easy ways that I can test these components without throwing my wallet at parts? Are there any other causes I should be thinking about?

Thanks in advance, please let me know if there is any other information I can provide. I do not have any fancy diagnostic software besides a cheap code reader; that has given me no information at all.

WavyQuantum5569 · Post by **WavyQuantum5569** » 10 Dec 2025, 16:44

I do have a video of one of the times I have had no throttle response. It may not be of any help at all but this is what I was referring to in my main post. I simply forgot to add it.

Post by **cuhfs** » 14 Dec 2025, 21:17

Read OBII codes. Have ignition coils and spark plugs been done? Just a thought.

Post by **scot850** » 16 Dec 2025, 14:44

Agreed, you really need to try to pull OBD2 codes or we are just guessing too, and that can get expensive quickly, let alone waste a lot of time all around.

Having been through something similar with a friends C30 Volvo and another friends S80 2.5T, there are many possible sources so here is where codes are a must to even make a start. There are many cheap scanners out there today which will cover most engine related codes, but it of course could be something else like the trans. Do you have any dash lights other than the check light of the engine?

Neil.

WavyQuantum5569 · Post by **WavyQuantum5569** » 16 Dec 2025, 20:33

I forget the exact make and model of the scanner I have experimented with, but I have not gotten it to give me any error codes. When I plug it in, it essentially says no issues detected. Perhaps I will have to get another one and see if that will do anything for me. Do any of you happen to know if there is a specific brand of scanner that is better for reading Volvo stuff?

I have not done coils or plugs and I do not see any service records indicating that those have been replaced during the previous ownership, but it was very well taken care of.

The "Reduced Engine Performance" along with a yellow warning light is always on, but that is the only message the car's display gives me that is relevant.

Cees Klumper · Post by **Cees Klumper** » 04 Jan 2026, 13:09

There are almost 100% certain trouble codes, given the messages in the dash. Maybe pay the modest amount needed to get a mobile mechanic who knows what they are doing to come diagnose it. Probably something simple and seems very worthwhile to fix the car. If you can still drive it, you can also go to an autoparts store, that typically scan codes for free for you.

WavyQuantum5569 · Post by **WavyQuantum5569** » 22 Mar 2026, 11:09

Hello all,

I wanted to give an update in the event it helps someone else down the line. I think I have found the solution to my problem. As I mentioned in my initial post, my S80 was stuck in limp mode and no code reader that I found was able to give me any kind of information about what was causing it. I did have an experienced mechanic friend take a look with his scanner and he was also not able to find an issue.

What I had forgotten to mention was that the air conditioning compressor had failed at some point. I drove the car without AC for quite some time as it did not give me any issues besides being hot. After inspecting my fuse panel, I found that a 10 amp fuse on the AC circuit had blown. I believe that same circuit must have some kind of ECM/ECU component on it. After replacing the fuse, it blew on startup, but then after disconnecting the AC compressor and replacing the fuse a second time, the car was out of limp mode because that fuse was intact. I have since purchased new AC components and will be having a shop do some work for me. Hopefully that will put the car back on the road once again. I don't know about any of you, but I never would have figured that a faulty AC compressor would cause the car to go into limp mode. Especially since I drove the car with the faulty compressor for at least a few thousand miles without issue. I wonder if it simply heated the compressor up enough to cause a short somewhere.

Tl;dr a short in my AC compressor blew a shared, ECM related fuse and caused my car to be in limp mode. I was able to drive the car without reduced power once I unplugged my AC compressor.

Vova585 · Post by **Vova585** » 22 Mar 2026, 20:49

I am quite skeptical honestly. No cause-effect relationship here. You were driving with ac system which was not working for a long time and had no "limp mode"..I see relationship between blown fuse and ac but not limp mode. I dont want to be negative, but I doubt. Before investing into ac parts and labor($800? My guess). Better buy yourslef vida dice clone for 120 or so(or pay dealer to do diagnostic $200) so you will be able to read history codes and see what was likely to cause the limp mode. Best to have your own scanner and erase all codes and try to drive a little(close to home) and see if the problem will be back. I am still thinking that it is throttle body issue(historically it is the most common and usually happenes around those miles). It is possible to get off limp mode for some time after several start-stop cycles, but not for long. You need capable tool to read codes which are not global obd. I am not faulting your friend, I have no idea what scanner he has and if it is able to read volvo specific codes vs just obs and live data available through obd. Also find the number of that fuse and invest into diagram for your car(alldata subscription is $25 per month) to verify what that fuse feeds. Once again, I would hate you to fix the ac and drain your wallet, just to discover it is throttle body or other component.
On the other note, car was sitting for a long time. Brakes are likely shot, tores with dryrot or cupping, unless your pcv system and timming belt were done shortly prior to failure...they are on the way too. Better pay dealer to inspect your car and give you a print out of codes(history as well), list of current issues and recommended maintenance. Then post it here and people will help you budget what can be done by you and friend vs needs to be done by shop and how much it may cost. Then make a decision if you want to rely on 20 year old car vs buying yourself other car with warranty.