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If your check engine light is illuminated and you notice your engine is suffering from poor idling or struggling to start properly, there may be an issue with its camshaft position or angle. Check the problem with your scanner—if it registers a P0012 code, read this guide to learn more about what it means and how to resolve it.

What Does the P0012 Code Mean?

Diagnostic trouble code (DTC) P0012 stands for “Intake (A) Camshaft Position Timing – Over-Retarded (Bank 1).” The code indicates that your car’s computer (also called the powertrain control module or PCM) has detected a difference in the desired camshaft position angle and the actual camshaft position angle. More specifically, the condition is set when the PCM detects that the camshaft has remained in a retarded position or that the camshaft timing on Bank 1 is above the maximum retard value.

Car camshafts and valve in oil on the engine
The P0012 code indicates that your car’s computer has detected a difference in the desired camshaft position angle and the actual camshaft position angle.

The “A” in the P0012 code refers to the intake camshaft in an inline or straight overhead camshaft engine. On the other hand, it refers to the intake camshaft on Bank 1 if the engine functions on a V configuration. 

“Bank 1” in the code refers to the side of the engine where the number one cylinder is located. Take note this applies to engines that employ a boxer or V configuration.

Note: Although code P0012 is a generic code specified by the Society of Automotive Engineers (SAE), the code’s definition may vary depending on the vehicle manufacturer.

An In-Depth Look at Camshaft Angle and VVT

The camshaft angle is only adjustable on engines equipped with variable valve timing (VVT).

With Variable Valve Timing (which is very common on today’s engines) camshaft timing can be altered dynamically while the engine is under load. This strategy is used to enhance fuel economy, increase power, and reduce tailpipe emissions. 

Dual OverHead Camshaft close up DOHC using VVT technology
The camshaft angle is only adjustable on engines equipped with variable valve timing (VVT).

So how does the Variable Valve Timing work?  The ECM/PCM sends a “pulse width” signal to the oil control solenoid, allowing the delivery of oil pressure, usually to vane chambers in the cam gear, which is designed to alter cam timing based. Some early VVT units used helical gears that moved in or out to alter camshaft angles. But to make this happen, the ECM/PCM turns the oil control solenoid on and off really fast. The longer the solenoid is on during each pulse, the more oil pressure is delivered to the actuator and the more cam angles are changed. When control oil pressure is reduced, a spring returns the camshaft to its default angle within the gear.

The Cam Sensor (CMP) on the bank being controlled provides feedback so the ECM/PCM can determine how much camshaft advance is needed (depending on engine load, speed, etc.) and how well the camshaft is actually being controlled by the action of the solenoid.

The ECM/PCM sets a target (desired) angle for the camshaft and then duty cycles the solenoid, delivering oil pressure to the camshaft actuator within the camshaft drive gear to change the relationship of the gear to the camshaft. If the camshaft angle is commanded to change the cam timing but it doesn’t happen or doesn’t happen quickly enough, the ECM/PCM maximizes the oil control solenoid pulse width in an attempt to force the cam angle change and then sets the P0012 code. 

What are the Possible Causes of the P0012 Code?

What causes a P0012 code? The likely reasons that prompted the PCM to log this specific trouble code include:

  • Bad or failing camshaft variable timing solenoid 
  • Bad or failing variable valve timing actuator
  • Low engine oil levels
  • Engine oil is incompatible with the manufacturer’s requirement for the engine
  • Worn timing chain
  • Failed timing chain guide or tensioner
  • Contaminated engine oil obstructing the VVT solenoid screen; NOTE: this is a common occurrence! Regular OEM specified oil change intervals using exactly the right kind of oil and always allowing the engine to reach operating temperature on every start will reduce the probability of the sludge that causes this.
timing chain of a vehicle
A worn timing chain or faulty timing chain guide can cause P0012 Code.

What are the Common Symptoms of the P0012 Code?

Warning signs that you have a P0012 code on your hands include:

  • Illuminated Check Engine Light
  • Engine struggles to start properly
  • Engine suffers from poor idling
  • Engine experiences stalling
  • Decreased fuel efficiency
  • Rattling noise from the engine

If your scanner reads a code P0012 and your car displays at least one of these issues, bring your vehicle to your mechanic as soon as possible.

How to Diagnose the P0012 Code

There are many problems that can trigger the P0012 code, from a failing camshaft variable timing solenoid to a worn timing chain. This can make an accurate diagnosis difficult, especially if you’re not an automotive specialist. Let an expert handle the task if you’re not certain with your car repair skills. 

On the other hand, if you feel confident in your automotive know-how, watch these helpful video references to get an idea of how to diagnose a p0012:

How to Fix the P0012 Code

Many OBD-II trouble codes share symptoms and causes, but there is no single way to fix them. The solution typically varies depending on the issue’s underlying cause as well as the vehicle’s make and model. 

For instance, a P0012 on a 2005 Ford F-150 can be resolved by topping up the engine oil, if that’s what’s triggering the issue. Switching out the timing chain or replacing the engine assembly are also confirmed fixes for this specific code on a Ford. Low oil pressure due to excessive bearing clearances can be the cause of this.

Still, the same solutions may not apply if your vehicle is a Toyota Camry or a Chevrolet Silverado. 

mechanic diagnosing a vehicle
Many OBD-II trouble codes share symptoms and causes, but there is no single way to fix them.

If you are not confident with your automotive knowledge and DIY skills, it’s best to leave the task to a professional. Otherwise, you can find the exact repair yourself by using online auto repair resources and guides and by consulting your owner’s manual before attempting to fix the trouble code to ensure that your solution is appropriate to your vehicle’s make and model.

You may also invest in an ALLDATA single-vehicle subscription, which will be useful in dealing with not only with the P0012 code but any other issue that you may encounter in the future.

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.

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