Hey guys. We recently gave our daughter our 2007 Maxima SL. It has about 90k on it and we recently had the timing chain tensioners and water pump replaced. She said the engine ran rough the other day when she came to a stop and the check engine light came on. She's at college so I had her take it to Auto Zone to have the code read. See the pic for the printout, but it says "Intake valve timing (IVT) control circuit failure". My daughter says the car seems to be running normally. Any ideas on what this would mean and would this be related to the work on the chain tensioner? Is there cause for concern if it's running fine? Thanks

 

The P0021 is for bank 2 of the engine, the side towards the radiator. P0011 is the other side, bank 1.

From the Nissan service manual, the possible causes are:
● Crankshaft position sensor (POS)
● Camshaft position sensor (PHASE)
● Intake valve control solenoid valve
● Accumulation of debris to the signal pick-up portion of the camshaft
● Timing chain installation
● Foreign matter caught in the oil groove for intake valve timing control

The 5th one in the list is timing chain related.
She could take the car back and have them look at it. To document this legally, she should send them an e-mail saying she has this problem and is going to bring the car in for them to look at it. Also, copy you (or someone) on the e-mail for backup purposes and of course make sure no one deletes it until this is resolved.

But the fact that the light has gone off makes any cause difficult to find. First of all, make sure the engine oil is full (possible cause 3 uses oil pressure). It may be that some foreign material got in the way and is now gone (possible causes 2, 4 and 6). It is normal for the check engine light to go off if the problem has gone away after some amount of driving.

Another note regarding oil pressure. If she came to a stop and the engine was idling rough, it was also probably idling slow. This would cause low oil pressure and could be why the check engine light came on. Rough idle has lots and lots of possible causes.

Link to the service manual I referenced. See page 162:
http://boredmder.com/FSMs/Nissan/Maxima/2007/EC.pdf

 

Thank you Dennis. The light is still on, however she doesn't drive it much. I was going to have her unhook a battery cable and see if that clears the light and see if it comes back. Kinda difficult with her away at school. Will definitely tell her to check the oil. Might have to wait until either she comes home or we go visit to do much else. If it does come back then I'll have to take it back to the local shop that did the timing chain work. Thanks again!