Full story: I have a 2008 XC70 3.2 with about 160k miles. I did an oil change and switched from Mobil 1 synthetic 5W-30 to LiquiMoly 5W-30 oil. During the oil change, I noticed the anti-drain plug floating around in the oil filter housing, put it back where it look like it belongs, and finished the oil change. Immediately after the oil change, I started the car and it idled very poorly. I immediately shut it off, checked the oil level which was fine, and got my code reader (generic Autel). After restarting and idling for a little bit longer, it started to smooth out a little bit. I took it on a short drive around my neighborhood and was able to get codes P0300 (Random misfire) and P0301, P0303, P0305 (Misfires on cylinders 1, 3, and 5). I was unable to find any common explanation between these cylinders (only things are being adjacent in firing order and ignition coils for cylinders 1, 3, and 5 all using one ground and 2, 4, and 6 using another ground) and reset the codes hoping the problem would either go away or that I could get a new code that would be more helpful. I repeated this a few times and consistently got misfires on cylinders 1, 3, and 5, occasionally with another cylinder as well (mostly cylinder 6). I pulled out the oil filter and installed a DIY replacement anti-drain plug, but didn’t get any improvement. Finally, I decided to take it on the highway and open it up a bit and was able to got the misfire codes again along with P003D. This is a generic code for a VVT issue, but the Volvo specific version is ECM-P003D00, which is described here (ECM-P003D00 – Volvo Diagnostic Trouble Code (DTC) Definition, Causes and Diagnosis). Perhaps notably, the description include “Hint: For this function, Bank 1 cylinders 1, 2 and 4 apply. Bank 2 regards cylinders 3, 5 and 6”, neither of which describe the grouping of cylinders that I am seeing misfires on. Based on this code, I ordered both a cam position sensor, and both types of VVT solenoids (different part number for intake vs exhaust). The solenoid seems more likely to have failed than the cam sensor, so I will be starting with that. Which solenoid should I replace? There is one intake solenoid on the driver’s side of the engine and one exhaust solenoid on either end of the engine. I am inclined to think the intake solenoid is the one that need replacement based on the explanation of the Volvo specific codes as well as looking at the replacement parts (the intake solenoid looks way more prone to getting stuck), but posters on various forums have described fixing related codes (P003F: A Camshaft Profile Control Circuit Stuck On Bank 2) by replacing exhaust solenoids and there seems to be contradicting information out there about whether bank 1/bank 2 refers to intake/exhaust sides, or to the grouping of cylinders described above and for which there are two exhaust solenoids.
Any assistance would be greatly appreciated.