So what are the part numbers needed to replace the sensors for the dreaded p0021 code?
I have ordered 2 996-105-301-04
I have ordered 1 997-105-303-73

car is an 08 997 turbo

 

996-105-301-04 --> these go on the heads....next to spark plugs and are not the source of fault for p0021. It is good to change them either way, but best done when you do plugs and coil packs.

997-105-303-73 will fix p0021 code for bank 2.

 

i appreciate it, thank you! does it make sense to replace both of the 997-105-303-73 at the same time?

 

the passenger side one is the more commonly failed one if you dig around posts and forums. Not sure why....but it is a mechanically actuated part and on two separate banks. The driver side one is actually easier to install than the passenger side one (easier tool access), but aside from removing the airbox...not really sure you are saving much time by doing one preemptively before failure. Rather take the coin and do the brake fluid flush or the oil change along with the air filter etc. I did only one and have been waiting since my original post for the other and it just hasn't happened.

 

got it, thank you! Im going to be doing an oil change at same time as replacing the bank 2 solenoid, :fingerscrossed that fixes it!

 

change oil and run it first if possible....then swap the solenoid.

 

Got home from vacation, fired up the car to go to work. Drove down the street and "beep" the cel came on. It was p1100 again. Looking back through my recent logs I could see exactly when the camshaft positions deviated. I reset the cel a couple of times and planned to change the oil. I had the same cel last year and a few years ago the actuator was changed at Porsche. Since my bank 2 camshaft replacement about 4 or 5 years ago I haven't had the bank 2 cel. I forget which bank is passenger or driver side. Anyway, you could feel the midband sluggishness and it didnt immediately get better so I started thinking about changing the actuators since my engine will have to come down at some point to replace the boost control hoses. I did a couple of third gear hard pulls and after that I could feel that the car wasnt sluggish anymore and the logs show the actual camshaft positions are in sync again. Don't know if it was debris in the actuator or the camshaft unspun itself but I will take the win! Hope it lasts!

 

Bank 1 = driver's side (LHD), bank 2 = pax's side.

 

Sometimes a good, hard drive can clear the debris.
Awesome.

 

Exactly!
So far so good. Logs show that the sync up takes about a quarter second or so. It seems to get closer each week. Last week it was about half a second. Not noticeable by driving but just seen in the logs. Not sure if that means the actuator is sluggish or the camshaft is partially rotated but I'll keep fingers crossed and just enjoy the car.

 

I just wanted to add that I now believe these actuators should be changed in pairs. I had a faulty driver side one which was not triggering any check engine codes but causing intermittent drivability issues. Every startup was like rolling the dice. One drive the car ran perfect and the next it might run like ****. Subtle hesitation, a weird stutter around 3k rpm and a general lack of power. I didn't think to suspect the actuator until after installing a Kline exhaust. I could hear the tone of the engine change when it was a good start and when it wasn't. I spend enough time commuting to pick up on these weird and very subtle changes as they happened. New actuator and everything has disappeared. I should of changed both when I changed the passenger side one a few years back. Maybe it slowly deteriorated and only just started causing issues, but honestly the biggest clue was the tone of the engine under acceleration with a catless exhaust that let me know I was not losing my mind.

All I want to get across is that these actuators "fail" ahead of triggering a check engine light.

 

Counterpoint: dealer replaced one of them (not sure which) and no issues after a few months and 1000 miles.