About 2 month ago, my son's S60 2.5T got both VVT solenoids were replaced and engine hot-flushed. The diagnosis was both oil filters on the solenoids were completely plugged and one damaged due to sludge build up. Well, 2 month later the codes returned. I wonder if anybody had that happened and what was the final diagnosis?
Also, is it possible that the PCV box is bad and needs to be replaced (i.e., would it give these 2 codes)?

 

What brand was used on the replacement valves? They respond through oil pressure so any issue there can cause the solenoids to not operate as expected. Did you also replace the gaskets? They need to replaced as well.

You can test your PCV by using the "glove test" or putting your hand over the oil fill while the car is idling and see if you feel a slight vacuum. Lots of videos online for the glove test. Hand test is just as efficient.

 

I do not know what brand was used - it was done by a mechanic. I'm sure they replaced everything that needed to be replaced. Th ecar uses a lot of oil, and I added about 3-4 quarts of 5w30. I wonder if that was the cause and I should have added 0W30 instead. We are going to change oil and filter again and possibly clean the solenoids and see what happens.

 

OE would be ideal for this part. When mine went, I spent a lot of time looking online and saw bad reports from people who used aftermarket parts. The aftermarket is a lot cheaper, but you might not get the longevity. Are you using 3-4 quarts of oil per oil change? Around 1 quart is okay on a car of this age, but 3-4 is a lot. So it would need to be determined if it is being burnt during combustion, or if it is leaking. I don't know if using a thicker oil would affect the solenoids that much with the small difference between 5w and 0w. Isn't 5w-30 the recommended oil weight anyways?

 

Yes, 5W30 is, but 0W30 is also. I wonder if the sludge in the system (despite hot engine flush) caused plugging of the screens. And yes, the car burns a lot of oil, but does not leak. Also, no smoke. However, my son uses a tuning chip (car has around 300hp right now) with fuel mpg at around 15, so I wonder if that contributes to the problem. Finally, I doubt both solenoids went at the same time. Both codes usually means oil trouble.

 

I agree with you there on all counts. Tune could definitely affect it.