I am almost sure it is a bad PEM.
Another location is inside the trunk.

There is a fuel pump relay soldered on the CEM circuit board. That car is not assured of having PEM as that is only for markets where evaporative emissions standards are strict. Look at the fuel injector supply manifold (fuel rail) and check if it has the grey and black fuel pressure/temp sensor ins...

Your fuel rail:

The only other place that I've seen the PEM mounted externally is right next to the fuel filter.
The 2.5T wagons and S60's are sometimes inside of the spare tire well.

Here is the Volvo code definition: https://www.dtcdecode.com/Volvo/CEM-3F91 You could test the pump by applying 12V to it. In the link above, Volvo says that the CEM (under the dash likely where the fuel pump relay is) can suffer damage if it is not unplugged when applying the voltage to the pump, s...

Ok, so not a ton of info on VIDA, but beyond what I had posted, it says in part, that: If the signal cable has been shorted to voltage, there is a risk of failure of an internal ground conductor on one of the circuit boards in the Central Electric Module (CEM). This may lead to the relay for 15-feed...

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