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Code P0021 is a generic powertrain code, so it is supported by various makes and models. It typically involves your vehicle’s variable valve timing (VVT) system. 

In this article, you will learn more about what variable valve timing is and its relation to trouble code P0021. You will also learn the common symptoms and the triggers related to the P0021 code. 

What Does the P0021 Code Mean?

Diagnostic trouble code (DTC) P0021 stands for “‘A’ Camshaft Position – Timing Over-Advanced (Bank 2).” It is triggered when the position of the intake camshaft in bank 2 is more advanced than what the powertrain control module (PCM) has set it to be. 

closeup of car engine showing intake camshaft and exhaust camshaft
Diagnostic trouble code P0021 is triggered when the position of the intake camshaft in bank 2 is more advanced than what the powertrain control module has set it to be. 

Usually, the “A” camshaft refers to the intake camshaft. However, take note that this is not always the case. What the “A” camshaft signifies may vary depending on your vehicle’s year, make, and model.

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Note: The definition of code P0021 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

More on Variable Valve Timing

The internal combustion engine has evolved throughout the years. One of its advancements is the incorporation of the VVT in a modern car engine. This component allows your vehicle to get more power and/or efficiency under various driving conditions. 

The PCM uses data from the camshaft position sensor(s) and crankshaft position sensor to determine the position of the shafts. Using that information, the PCM commands a VVT solenoid to apply oil pressure to an actuator on the end of the camshaft. As a result, the actuator alters the position of the camshaft, thereby changing the engine’s valve timing.

You can find more technical information in our in-depth discussion about the camshaft angle and VVT.

What are the Possible Causes of the P0021 Code? 

Below are the possible triggers of the P0021 code. Note that not all vehicles come equipped with VVT and that causes may vary depending on your vehicle’s year, make, and model. 

  • Faulty valve variable timing actuator
  • Worn or damaged timing chain
  • A failed timing chain tensioner or guide
  • Low engine oil
  • Stuck or defective timing valve control solenoid
  • An issue with the PCM, such as software in need of an update
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closeup of automotive timing chain
A worn or damaged timing chain is a common cause of the P0021 code.

On a 2003 Nissan Altima

As mentioned, possible causes may vary depending on the vehicle. For example, these are the possible causes of P0021 listed for a 2003 Nissan Altima:

  • Harness or connectors
  • Intake valve timing control solenoid valve circuit is open or shorted.
  • Intake valve timing control solenoid valve
  • Crankshaft position sensor 
  • Camshaft position sensor 
  • Accumulation of ferrous metal debris to the signal pick-up portion of the camshaft

What are the Common Symptoms of the P0021 Code?

Aside from an illuminated check engine light, here are some common symptoms related to the code:

  • Hard starting
  • Poor or rough idling 
  • Rough running 
  • Stalling
  • Poor fuel economy
  • Rattling noise from the engine 

How to Diagnose the P0021 Code 

It may be difficult to diagnose the P0021 code, given that the symptoms associated with it may also be a sign of other faulty components of an engine

It is also important to note that diagnostic and repair steps for OBD-II codes may vary depending on the vehicle’s specific year, make, and model. For example, diagnostic procedures for a P0021 in Nissan may differ from the process for a P0021 in Subaru. To be sure, it is best to have your vehicle checked by professionals.

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How to Fix the P0021 Code 

Most people leave the repair job to their mechanic, usually because they lack the skills, knowledge, and experience essential for the task. However, that doesn’t mean that you can’t fix the issue yourself. 

Just make sure you have the necessary equipment on hand and adequate DIY automotive skills. Rely on online auto repair resources and guides or get an ALLDATA single-vehicle subscription to get helpful information.

Products Mentioned in this Guide

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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