P0021 is a common trouble code. It affects vehicles with variable valve timing (VVT). The list of VVT vehicles is growing, and the Nissan Altima can have VVT, and is prone to developing this code.
P0021 is a generic OBDII code. This means that it has the same definition regardless of the make or model of the vehicle. It has the same definition for the Nissan Altima as it does on any other vehicle. Bank 2 refers to the issue being on the side of the engine with cylinder 2 in the firing order. For the side of the engine with cylinder 1, the code would be P0011.
VVT changes the frequency and distribution of gases entering and exiting the combustion chamber. It allows the engine to act as though it has different camshaft profiles at different RPM’s. This is great for both power and fuel economy.
P0021 Definition Nissan Altima
The Nissan Altima utilizes camshaft actuators to change the valve lift depending on the RPM of the motor. This allows for a more efficient cam profile at any speed. When the timing is too far advanced
Camshaft Position Actuators change the lift of the camshaft up to 25 degrees. They are hydraulic, which means that they use the vehicle’s engine oil to control lift. So, if you have low oil pressure or dirty oil, it can keep them from doing their job properly, and trigger P0021.
With P0021, the camshaft actuator is leaving the timing too far advanced, or there is a system performance issue (not working right).
Nissan Altima P0021 Symptoms
When the timing is too far advanced, it can really cause some issues with the motor. Here are some of the typical symptoms of P0021 in the Nissan Altima:
- Poor Idle Quality– If the camshaft actuator fails while giving the engine aggressive valve timing, it’ll idle roughly.
- Decreased Gas Mileage– Now the engine can no longer adjust its cam timing on the fly, it will no longer be able to produce optimal combustion which equals poor economy.
- Lost Power– The engine will not be able to produce as much power. This is because the cam profile will not allow it run a performance power curve when you need more power.
- Service Engine Soon Light– Most of the time, you’ll be able to feel or see one of the above symptoms, but if you can’t, the service engine soon light will still come on and let you know that something is wrong.
- Tough to Start Motor– With the timing too far advanced, it is going to be difficult to start the motor, especially when it is warm.
Possible Altima P0021 Causes
There are quite a few different things that can cause the P0021. Here are the most common causes:
- Engine Timing– If the camshaft(s) are no longer synced to the crank properly (such as if the timing chain jumped a tooth), it can cause the engine timing to be off enough to throw the P0021 even though it’s not the Actuator’s fault. Here’s more on that from this site: Timing Chain Jumped Symptoms and Diagnosis
- Engine Oil– If the engine oil is dirty or low, it may cause the actuator to function improperly. Also, the oil viscosity can be off
- Bad Intake Camshaft Position Actuator Solenoid– The actuator solenoid itself can go bad over time. You certainly don’t want to start here, since a lot of the time it’ll be something else that causes the P0021 to appear. Here’s a good video of someone replacing one, so you can see what goes into it. If you find you need one, they typically aren’t that expensive.
- Wiring Issues– The wiring going from the solenoid to the ECM can become damaged or broken. This will throw the P0021 OBDII code. The wiring harness to the intake camshaft position sensor may also develop a poor connection. YouTube: How to Find an Open or Short the Fast Easy Way.
- Bad ECM (highly unlikely)- If the Altima’s computer goes bad, then it may throw this code along with other issues. Here’s how to tell if you have a bad ECM Autoblog: Symptoms of a Bad ECM.
Here’s a phenomenal video on how to test a cam/crank actuator. It’s on the page instead of a link because it’s that worth watching. Always make sure that you check everything else that you can before actually opening up an engine.
Conclusion
If it has been an excessive period of time since the last time that you’ve had an oil change, or you find that there may be reason to believe that the oil thickness is wrong, change the oil and see if that helps anything. Good luck diagnosing the P0021 in your Nissan Altima. If you would like to add anything, please leave a comment below.