P0021 Fault Code

Long Description

Fault code P0021 is the code used when the engine control module (ECM) has detected the intake camshaft in bank 2 is further ahead in its cycle than desired.

This occurs when the ECM is unable to correct the over-advancement of the camshaft in the second bank.

This can cause a wide array of issues with how the engine runs because the timing can be thrown off.

Camshafts are responsible for a host of engine operations but are typically responsible for ensuring the correct timing of the valves which control the amount of air or fuel in a given cylinder.

They need to be precisely in time with the rotation of the crankshaft to achieve proper operation.

This code only applies to engines that have two banks like a V6. For the same code for inline engines, see P0011.

Again, only engines with two banks are able to have this fault code logged. Cadillac, Subaru, and Nissan vehicles with V-shape engines are some of the most commonly associated with this issue.

Other Signs of This Problem

Because of the severity of the issue, there are several very noticeable symptoms of an over-advancing camshaft. The first is that the Check Engine light will be illuminated or flashing.

The other signs involve just about every aspect of the car running. Idling, starting the car, and accelerating will all be very poor. The vehicle may also inexplicably stall or misfire.

Another sign is a rattling noise from the engine due to unbalanced forces in the various components.

Other camshaft position errors range from P0010 up to P0014. Additionally, crankshaft errors are P0016 and P0017.

What Could Be The Problem?

The most straightforward cause is due to the camshaft and crankshaft sensors indicating that the camshaft is too far advanced before the ECM is able to correct it.

A faulty camshaft actuator or variable valve timing (VVT) solenoid should also be checked as these both have the potential to disrupt the desired timing.

Issues with the oil system can also cause this error code.

If the engine oil is too low or too dirty to properly lubricate the camshaft, it can cause the VVT solenoid to stick. Contaminants in dirty engine oil can prevent proper VVT operation.

A damaged or stretched timing belt or chain can also lead to this breakdown in the correct timing.

Fixes

If there are issues with any of the moving components like the camshaft oil valve or solenoid, replacing these parts can help return the vehicle to proper operation.

Check the oil for metallic flakes, dirt, or any other contaminants. Checking the oil filter can also help determine if the issue is here. If there is an issue with the oil, be sure to replace it with the correct oil.

Ensure this oil is fresh and has the correct viscosity for your engine. It is important to use the amount recommended in the owner’s manual.

Replacing a damaged or worn timing belt or chain can also rectify the issue. The timing chain should also be checked for the correct alignment.

Seriousness

Fault code P0021 is a serious issue. Improper timing can cause serious damage to a host of components and result in very expensive fixes down the line.

It is a good idea to have this fault code fixed immediately.