Hi all,

This is my first time posting on this forum with the hope that you all might be able to help me with an inexplicable and nightmarish (and very expensive) experience (rough idle/stalling/power loss) with my 2012 Volvo S60 T5 Turbo (120,000 K / 74 K Miles). Note: I've done lots of searches for this particular problem, but nothing that satisfied what's been going on with my particular car.

The long story is that the car was purchased used with around 95,000 KM in October of 2020, and ran like a gem for the first year and a bit. Around April of this year (2022), just when the weather started warming up, I began to experience an intermittent rough idle issue which was at first attributed to the engine coils, and which were very promptly replaced (all five of them). The issue went away for about one day before returning very shortly thereafter, it was then suggested that I get a new spark plugs, this was also done promptly.

Once again, the issue persisted and to date I have put in about 4-5 thousands dollars worth of equipment, and labor by replacing the following parts (all Volvo OEM): Engine Coils, Spark Plugs, Throttle Body (ETM), Fuel Pressure Sensor, New Throttle Pedal, MAF. And the issue still continues. The symptoms I experience are a consistent rough, intermittent, idle where it is "hunting", on other occasions it loses power briefly so that even when I step onto the accelerator pedal it doesn't move the RPM. I have found that this most often happens on particularly hot days, and when the AC is engaged. At other times, the car drives fine with the Reduced Engine Performance on the dash. Another observation I have made is that when this occurs, and the vehicle is in park, and I step onto the accelerator pedal and rev up to the max, the "Reduced Engine Performance" will suddenly go away, and the car's RPM's will settle down and allow me drive normally before the problem returns with a vengeance a few hours, or a few days later. One more observation: the limp mode also seems to be triggered when I'm trying to accelerate slowly from a relatively low speed, let's stay 40 - 50 KM to 60 - 70 KM, there is a feeling that the engine struggles (no audible noise) but you can definitely feel it, and instantly "Reduced Engine Performance" pops up again. *Sorry for so many details, I realize it may cause more confusion but I figure it's best to offer all I've observed rather than too little.

I fortunately have a good friend who has access to a VIDA Dice Tool, and the most persistent codes look like this:



It was based on these codes that we have replaced the ETM (Throttle Body), MAF, Fuel Pressure Sensor, even threw in a new accelerator pedal and still no improvements have been observed. We also thought that this might be an air leak but three garages have now checked the pipes (including the local Volvo dealer), and nothing appears (I can't say for certain that an actual smoke test has been done on it). I have also now paid Volvo a few hundred dollars to have them update the various software modules but only one day later it went back into Limp mode ("Reduced Engine Performance", "Engine System Service Required") with a rough idle (with surging), engine shaking, and I had to tow the vehicle to Volvo (where it still remains). I'm not too optimistic that they're going to come up with anything new as their first suggestion was to replace the ETM which I have already done, amongst so many other things.

I'm genuinely at a loss at this point, and my bank account has been hit hard from the various parts and labor put into this car especially as the vehicle has been quite well-maintained, and I'm keen to avoid throwing more money into this without getting additional input. Could this be related to the AC somehow? I have also thought of replacing the MAP, oxygen sensors, perhaps a new oil trap - all things that I understand could lead to rough idle issues. If there are any suggestions, or similar experiences any of you may have, it would be super helpful to hear from you. Please ask any questions and I'll try to answer and hopefully this thread might be able to help someone else experiencing a similar conundrum. Thanks for reading, and for any help!

All the best,
Adam