I just recently purchased a 2003 g35 sedan out of my home province with 125k kms on the dial. Brought it back here and now need to pass a provincial safety and emissions test. No problem I thought, it looked minty and well taken care of and no check engine lights so shouldn't be too hard to pass emissions. Took it in to a Nissan dealer here, passed safety no problems, but failed emissions due to a p0021 code. Weird, I thought, because there was never any SLS light on that I would normally associate with this code (bank 2 intake timing advanced).

So I took it home, scanned it with my own scanner, sure enough there was the code. Cleared it, drove around, it reappeared. Searched through the forums, found that the culprit is usually a faulty camshaft position sensor (backed up by the dealer because they quoted me at $600 to replace it). So I ordered the sensor in via overnight shipping to get this over and done with asap. Swapped the sensor, ran the car, no codes. Perfect.

I drove the car for the day in order for it to complete one full driving cycle so it could go back in to pass the emissions test. Before taking it in I ran my scanner one more time. Boom. There it was again. P0021. Strange that still no light was associated with it.

So at this point I'm worried. Beyond replacing the sensor, there doesn't seem to be a lot of solutions to fix the code. Some say it can be caused by low oil; however, my oil levels seemed fine (dipstick is a pain in the *** to read). Either way I drained the oil and replaced filter and filled it back up with 5w-30 full synthetic.
Others say it could be because of deposits and build up in the ivtc solenoid valving. So I removed it, cleaned it up as best I could by blasting it full of seafoam and draining/drying it out then re torqued it back on. Beyond replacing the ivtc solenoid with a brand new one from the dealer or a known functioning one from a parts car, what other options are there to solve a p0021 code?

Part 2 of my problem: obviously the previous owner disabled the SLS light. My fault for not noticing that it doesn't come on during startup when I originally went to go see and purchase the car. So how would one go about disabling the light, and more importantly, what's the best way to reverse it? I haven't pulled the dash yet but I imagine that's what will eventually happen. I've read that it's an led soldered onto the main board. Would it just be easier to source a dash out of a parts car and roll the odometer?

TL;DR: How do I fix a p0021 code beyond cleaning ivtc solenoid valve and replacing camshaft position sensor and flushing oil AND how do you disable the SLS light and how do I reverse the damage?

 

It could be the camshaft, crankshaft, timing chain, IVT solenoid, low oil, or just dirty.

Sometimes the car will store a pending code before actually setting the CEL.

If you have a multimeter and some alligator clips you can test the IVT solenoid to make sure it actually works.

Take of the driver side IVT solenoid.
Check resistance between terminal 1 and 2. Should be between 7-7.5 Ohms around 68 degrees, if it's significantly higher or lower the valve is probably bad. It will vary a little bit depending on the actual temperature.

Check resistance between terminal 1 with ground. No continuity should exist
Check resistance between terminal 2 with ground. No continuity should exist

Hook the solenoid to the battery with alligator leads for a few seconds to see if it turns on.

Test resistance for crankshaft and camshaft sensors
Terminals 1 and 2 - Shouldn't be 0 or infinity
Terminals 1 and 3 - Shouldn't be 0 or infinity
Terminals 2 and 3 - Shouldn't be 0 or infinity

 

Awesome reply! When you say the crankshaft or camshaft, do you mean the physical shafts themselves or the sensors associated?

I'm just wracking my brain trying to figure out how it could be anything but a sensor if the car runs, drives, and idles perfectly fine.

I'll test the IVT solenoid tonight but Incase it tests fine, what would be the next step? It seems like anything beyond that indicates tearing down the engine (which I guess is why the PO went through lengths to hide the CEL).

 

You just unhook the wire harness from the sensors and test the pins. If you didn't use an OEM camshaft sensor originally, I would replace that one with one from Nissan/Infiniti. Always, go OEM with most sensors especially the MAF and cam/crank sensors.

I would re clean that solenoid also and not use SeaFoam, which is usually for carbon buildup. Spray the inside of sensor with brake cleaner and the contacts with MAF or electrical cleaner.

See if you have any major oil leaks it works off oil pressure. I goofed up a few months ago when I replaced the gaskets for VTC while I was doing my valve covers. I forgot to tighten down the VTC solenoid and had oil all over my driveway and engine bay.

If your solenoid fails the test then I would buy a new or used one from eBay or something.

Worst case scenario is it's the camshaft or the sprocket I guess.

 

Used a Hitachi sensor (who builds the OEM ones) so no reason to think it's the sensor, however I could still test it. No major oil leaks, was sitting at full this morning before I drove it and code came back by the time I parked it. I'll try sourcing a known working used vtc module first and clean it out with brake cleaner and electrical cleaner. I used seafoam and degreaser thinking that it'd be enough to clear any larger deposits that would be affecting it.

The dealer I bought it off is willing to take the car back because of the disabled CEL light so now it's a question of whether to keep going down this rabbit hole or cut losses and look for something I can register in my province

 

If they're willing to take the car back because of the disabled CEL, I would stop investing time and money in this car and give it back to them.

Odds are if that was disabled on purpose it's probably something worse or more expensive than checking/replacing sensors. I'd cut your losses, get rid of the car, and look for a replacement.

 

^^ agreed. Seems like this is an absolute nightmare to deal with after all the easy fixes. Such a shamsince the car runs and drives fine and is otherwise mint.

 

Disappointment now better than a bummer later.

 

I had a similar problem with a VQ35 Maxima but it was the P0011 code. Not matter what I did in the 82,000 miles I owned the car, it was an irritation. Usually wouldn't show up unless I bumped the rev limiter or spun the tires hard (which was easy to do with summer tires on cold pavement in the winter) and even though I never got a CEL, my car would go into limp home mode, I'd have to turn off my car, turn it on to run (but not start) to clear the pending code, then restart and it would be fine for a while. Changed the cam position sensor, cleaned the solenoid, everything checked out but hit that rev limiter or spin the tires excessively (which I tried not to do obviously) and it would be a problem. Never kept me from passing inspection though because it wasn't a constant problem. But I was never able to solve it. No issues with my second Maxima or my current G35.