2005 XC90 p0027 code, replaced exhaust solenoid - Now p0079

dontGo2Goa · Post by **dontGo2Goa** » 07 May 2015, 13:20

My 2005 XC 90 threw a P0027 (exhause valve solenoid) error code, immediately after changing the oil. I assumed the exhaust solenoid became clogged, and so replaced the solenoid with a brand new part and gasket and now the P0027 error has been replaced with P0079 (exhaust circuit low) error code.

I can only guess that, either the VVT pulley is going out, or perhaps it's a wiring issue to the exhaust solenoid.

Question: Could it be a wiring problem? How do I test the circuit to the exhaust solenoid? I have a multimeter, but not sure how to test this.

Also, if the wiring is good, could it be the VVT pulley? How can I test the VVT pulley to see if it needs replacing? Can the pulley be serviced (it's expensive)? If I replace the VVT pulley, will I need to redo the timing on the vehicle? years ago, I did the timing on my xc70 and I still have the cam locking tools, along with the TDC tool, but it was a major pain and I don't think I can remember how to do again this after several years.

Thanks to anyone who can share some insight here.

dontGo2Goa · Post by **dontGo2Goa** » 09 May 2015, 10:08

So, upon further investigation, I placed a rubber glove over the oil filler opening and it began to inflate, indicating a positive crankcase pressure. Small, barely perceptible puffs of smoke also emitting from dipstick tube when oil dipstick removed and oil filler cap in place. All very strong indicators of a clogged PCV system. Two years ago, I replaced the PCV on my other Volvo, an XC70, and so I'm well aware of how problematic these systems can be.

The exhaust cam solenoid is operated via current and oil pressure, so I'm hoping that when I replace the PCV system, the exhaust cam solenoid / P0079 (previously P0027) issue will be resolved.

Also, a high-pitched whirring, turbo-like sound, increasing in pitch during acceleration, has recently developed. I suspect that this is related to the PCV system and will disappear after I do these repairs. I plan to check the cam seals and anything else that could have been affected while the PCV system was clogged. Any particular items I should look into while doing these repairs?

Will post results once this issue is resolved.

dontGo2Goa · Post by **dontGo2Goa** » 31 May 2015, 13:55

Replaced PCV oil trap and associated hoses. As you can see, it was badly clogged and needed replacement. Cleaned out the ports on the block and put in new unit.
Started car, drove for a bit, shut down, restarted and CEL came back, once again with P0079.

At least it wasn't a wasted repair. Now I'll probably have to pull the oil pan and replace all seals, even though oil pressure seems good. Next on my list is the variable valve timing pulley and if that doesn't do it, I'll assume the engine has some kind of chunk clogging it up and I'll have to junk the vehicle or get a new engine.

Any thoughts?

brothermatt · Post by **brothermatt** » 24 May 2016, 13:05

Did you ever resolve this?
I'm having what may be the same problem with a P0079 code. I have done almost everything I can to resolve the issue. Unfortunately, I fail the smog test automatically because of the check engine light.
-Replaced the exhaust CVVT solenoid
-Replaced the exhaust CVVT hub
-Replaced CVVT solenoid's pigtail wire
-Confirmed that the wiring to the CVVT solenoid is good by checking for circuit continuity
-Oil is clean and changed regularly, engine timing is correct, camshaft position sensor has been tested working.

I am now in the process of ordering a cloned ECM. I opened up my ECM and the pin that drives the solenoid and the components around it all look to be in good condition with no corrosion or burns. It's just the last item that I can think of that could be causing this. I am curious if you resolved this and what the problem wound up being.

Koberunsdis · Post by **Koberunsdis** » 27 Oct 2021, 23:14

Did you find out what happened? My car is having the same problem

Post by **RickHaleParker** » 28 Oct 2021, 07:51

Koberunsdis wrote: ↑27 Oct 2021, 23:14 Did you find out what happened? My car is having the same problem

The posters above have not logged in for over a year.

For ECM-616D (P0079) Clean the connector on the Exhaust Camshaft Reset Valve and check for shorts between the wires. If that not it, replace the Exhaust Camshaft Reset Valve.

brothermatt · Post by **brothermatt** » 28 Oct 2021, 13:20

Koberunsdis wrote: ↑27 Oct 2021, 23:14 Did you find out what happened? My car is having the same problem

-If you order a replacement solenoid, make sure that it isn't a refurbished unit.
-Impedance across solenoid pins should be 3.7 ohms.
-If you apply 12v across the pins, you should get a strong, audible click.

In my case, Volvo supplied a faulty part... twice.
As I mentioned in my previous response, I purchased a VVT solenoid from Tasca Volvo. I installed it with along with a fresh gasket and the code came back. I continued diagnosing every component in the fault path, even replacing some of them. I wired and tested the VVT solenoid and found that it was faulty so I ordered another one from Tasca under warranty. I installed that one and the code and CEL returned in short order. I wired and tested this 2nd unit, and it was also bad. I ordered a third unit, this time from FCP Euro. That unit finally resolved the issue and is still on my car today... with FCP's lifetime warranty.
1) Up until that point, I had never received a DoA or defective/fast-failure part from Volvo.
2) The first two units came in the blue Volvo box as expected but they had a sticker on them that said something like refurbished or reconditioned. The third one from FCP did not have that sticker.
3) Between the headache caused by these defective solenoids and the way that Tasca responded to another issue with a fuel pump, I will never buy anything from them again.

Post by **RickHaleParker** » 28 Oct 2021, 13:56

brothermatt wrote: ↑28 Oct 2021, 13:20 1) Up until that point, I had never received a DoA or defective/fast-failure part from Volvo.
2) The first two units came in the blue Volvo box as expected but they had a sticker on them that said something like refurbished or reconditioned. The third one from FCP did not have that sticker.
3) Between the headache caused by these defective solenoids and the way that Tasca responded to another issue with a fuel pump, I will never buy anything from them again.

FCP Euro is cost effective not cheap.
I have pretty much given up trying to convince the masses that cost effective and cheap are not synonyms. Cost effective is what a person should seek out.