So the other day check engine light came on with a P0021. I cleared the code and has not come back yet however I was looking at scan tool data and timing was showing -15 on bank 2 and 0 degrees on bank 1. My question is this normal or does this mean bank 2 cams are off a tooth. From what I have read P0021 means that it was advanced more than it was supposed to be not retarded. I drive a 03 g35 sedan thanks for any hel

 

P0021 means the ECM is advancing the timing but the cam sensor is sending back a value that is outside the range it should be.

At idle both banks should be close to zero degrees, 2k rpm it should be up closer to around 30 degrees on each bank.

Low oil pressure can cause lack of advance but it would typically be on both banks. On the HR engine it is pretty notorious for blowing the rear galley gaskets and throwing this code. On the DE it's more common that the cam actuator is getting plugged up with debris or is simply not actuating properly. You can remove it and visually inspect the screens, you can also apply 12v to the solenoid (recommend using a dummy harness and putting a momentary switch on the hot side so you can rapidly actuate without any arcing on the harness pins) the solenoid sometimes gets something jammed in it that won't let part of it open all the way.

If you don't want to bench test you can always just install a new one.

Cam sensor failing and sending the wrong data can also make the ECM think the cam advance is not being reached.

 

So I checked the solenoid for bank 2 and it ohms out at 8.5 I checked operation and it moves just fine. I can see timing move with scanner when revving engine. And I had a spare cam sensor so I tried it and it still shows -15 degrees at idle on bank 2. 0 degrees bank1. I am thinking maybe the chain tensioner is bad that goes between the intake and exhaust cams. I am wondering how hard would it be to replace. Can I take the valve cover and the oil block out to replace it or does the hole front cover have to come out?

 

As I understand, when the upper tensioners fail you'd be getting a gnarly rattle/grind noise, particularly at start up. I haven't heard of anyone replacing one on a VQ with the timing cover still in place.
I believe that the vtc actuators also allow a path for the oil to drain from the sprocket, so even if the solenoid functions, it may not be allowing oil to recirculate. I would still try a new VTC actuator before attempting to replace the tensioner. Easiest part to replace, thus easier to rule out. Most auto parts stores have a lifetime warranty, so if that doesn't solve the problem you can just return it and get your money back for the part.
Also, it could be the VTC sprocket itself has failed. I saw a picture on Reddit a while ago where the inner sprocket shattered, but it seemed bizarre for that to happen. I can imagine the engine made an awful noise when it broke.

 

I does make a noise but it sounds like an exhaust rattle at about 2000 rpm. No noise at idle or start up. I had the motor rebuilt at about 20000 miles ago and it is just now getting the p0021 code. I did recently change the oil about 1000 miles ago. I switched to synthetic 5w 30. I was using strait 30 weight that the builder suggested. I should be broke in by now.

 

I does make a noise but it sounds like an exhaust rattle at about 2000 rpm. No noise at idle or start up. I had the motor rebuilt at about 20000 miles ago and it is just now getting the p0021 code. I did recently change the oil about 1000 miles ago. I switched to synthetic 5w 30. I was using strait 30 weight that the builder suggested. I should be broke in by now

 

So I took the vvt solenoid out and cleaned it with parts cleaner. I have put about 100 mile on it since then driving through downtown Houston. No more p0021 but when I look at timing I still shows -15 at idle for B2. I also bumped ignition timing up 2 degrees I feels like a new car.

 

I’m wondering if you ever had any more problems out of it?