2010 Volvo XC60. alright I’ve been chasing this check engine light, I’m trying to flip this. let me explain what I’ve done so far. this is kinda long because I’m trying to be as detailed as possible. Skim it, idc, but please help if you can.

Based on research I did, I thought it might be a bad sensor and so I tried removing the sensor from the original radiator in which attempt I poked a hole in the radiator.

Bought a Volvo OEM radiator from FCPEuro. Installed it cleared the code, it drove without a check engine light for a couple of days - this was awesome. But eventually it came back on.

I was stumped. I read the Tech Journal about how it needs a ECM Upgrade. I don’t have VIDA or the desire to pay the money it costs for the membership and all that stuff. and so I took it to the dealership ready to pay a Volvo tax.

Long story short they blamed the brand new genuine Volvo part as faulty. They said there weren’t any updates available for the ECM and gave it back to me.

So I wanted to believe the dealership was telling the truth. In an attempt to fact check them I did some testing with a multimeter.

I plugged the sensor in, backprobed the signal wire on the sensor and it came back reading ~ 10v steady. (note battery was at a healthy 12.5v) I can’t seem to find information about what it should read at, but seeing it’s a LIN communication device I think it should be less than that and it should be fluctuating up and down. Right?

Also when the sensor is unplugged the signal wire from the harness side reads 0v.

With this voltage reading I assumed the sensor was bad. Plus all I could find online (which isn’t a lot) made it sound like this means this sensor is bad.

So I got FCP to mail me a replacement radiator. I took out the new radiator and the “new new” one got here.

So after getting the “new new” radiator, I haven’t installed it yet but I plugged in just the sensor by leaning it up against the front bumper, and it has the same voltage readings. So there’s no WAY that I got two faulty sensors.

So the tech journal says that if you have the two codes I have together without history of an alternator code perform an “ECM Upgrade”. I thought Volvo might’ve known what that meant and did it. But they said they checked for any available updates.

That’s not what this is saying I don’t think. I’m pretty sure it needs a reflash, like remove the current ecm software and reinstall it. Off and on again type thing.

but I honestly have no idea if that’s true or not. Was the dealership just not knowing where to look?

is there something I don’t understand about this system?

is that signal wire voltage normal?

Im out of ideas. I’m going to just reinstall this “new new” radiator and take it to a Volvo (non-dealership) shop and ask them specifically if they can do a reflash for this. That’s my last guess.

But if someone here has some awesome Volvo Lin communication knowledge to dispel on me I would be most grateful.
Here is the repair order from the dealership. Circled in red is their diagnosis.