S90 Crankshaft Sensor Error

Whoa, 'Crankshaft to camshaft reference value' eh? That sounds like a sync issue between your crank sensor and cam sensor. Basically, the ECU is getting conflicting signals about where the engine is in its rotation. Misfires galore, I bet! Have you checked the wiring to both sensors? Rodents love chewing on those things. Also, is it rough at idle? What happens if you rev it hard?

Thanks for the quick reply! I haven't checked the wiring yet, I'll take a look tomorrow when it's light out. Idle is a little rough, yeah. When I rev it hard, it seems to struggle to get up to higher RPMs and feels like it's holding back. Could it actually be a faulty sensor, or is it more likely the wiring?

Alright, rough idle and struggling at high RPMs with that code? Sounds more and more like the crank sensor is going bad. Sometimes they get heat-soaked and start sending garbage signals. While wiring issues are possible, a failing crank sensor is the more common culprit with those symptoms, especially at that mileage. Honestly, I'd bite the bullet and get it properly diagnosed at a workshop. They can scope the signals and be sure before you start throwing parts at it. But yeah, that code screams crank sensor to me.

Okay, thanks a lot for your help! Took it to my local mechanic, and you were spot on – it was a defective crankshaft sensor. They replaced it, and the total bill came to 340€. Car is running perfectly again!