Error Code P0015 is defined as Camshaft Position B – Timing Over-Retarded (Bank 1). This refers to variable valve timing (VVT) or variable camshaft timing (VCT) components and the vehicle’s powertrain control module (PCM or ECM).

Definition

This error code is actually a generic code that indicates the PCM (or ECM) has determined a problem in the exhaust camshaft timing in bank 1. The problem refers to the camshaft’s timing, in which it’s over-retarded (delayed) compared to where it should be. This over-retarded issue can occur in either advancing or retarding phase. This means the camshaft and crankshaft timing is off, and that the camshaft is behind from where it should be in relation to the crankshaft. This primarily causes issues with the overall running of the vehicle and potentially impacts engine performance.

The PCM seeks better timing through variable valve timing (VVT), and the latter uses several components such as sensors, solenoids and control valves connected with the ECM to adjust and monitor the engine’s mechanical camshaft valve timing. The VVT doesn’t only help the performance of the engine, but more importantly, it regulates the vehicle’s fuel mileage through advancing/delaying the timing of the camshaft, depending on the needs of the vehicle.

Both intake and exhaust camshaft timing are typically delayed at higher RPMs for improved power.

At times where the VVT is used on exhaust camshaft in an OHC (overhead camshaft) or DOHC (dual overhead cam), engine delay is also sometimes used to lessen the NOx (nitrogen oxide) emissions when under load.

Common Symptoms

Aside from the illuminated Check Engine light, some of the common symptoms of this error code include:

  • Hard starting
  • Rough idle
  • Stalling
  • Engine misfiring
  • Poor engine performance
  • Poor fuel mileage

Possible Causes

Error Code P0015 can be caused by multiple factors, such as:

  • Incorrect shifting of camshaft
  • Defective Variable Valve Timing (VVT), stuck open, compromised oil flow control valve (sticking), caused by varnish buildup or oil contamination.
  • Electrical shorting in wiring in VVT oil flow control valve, causing it to consistently receive voltage
  • Broken camp phaser spring (for helical gear phasers) or stuck camp phaser in full retard position (stuck open)
  • Continuous oil flow to VCT piston’s chamber

How to Check

To diagnose the vehicle with this error code, technicians conduct a visual inspection of the connections and wiring of the OCV. He will then check the engine oil to see if it still has the correct viscosity and that there’s enough oil in the engine.

Of course, technicians will use an advanced scan tool to check the status of the VVT oil flow valve. Typically, it should be On at higher engine RPM and Off at idle.

He will also scan and document the engine codes and check the freeze frame data to see exactly where the code was set.

The technician will then reset the Check Engine light and test drive the vehicle to see if the code re-appears.

He will also command the OCV on and off with the scan tool to see if the timing of the camshaft changes.

Many vehicles provide a manufacturer’s test for this error code, and their troubleshooting can usually narrow down to the root cause of problem.

Doing the diagnosis and troubleshooting the wrong way may lead to internal engine damage. It is crucial to have an expert technician check your vehicle for this error code.

How to Fix

The main component to check in this error code is the performance of the VCT solenoid.

If the VVT oil flow control valve solenoid is defective, then you need to replace it. If this still doesn’t solve the problem, then there must be a problem in your cam phaser (stuck open) and may need replacement.

Oil and filter change is extremely important when you replace either the phaser or the oil flow control valve, as dirty oil may cause a buildup of sludge in the valve and phaser.

Also, make sure you refer to your vehicle specific manual before you perform any tests for the VCT unit. Dealers and technicians usually have the necessary tools to thoroughly diagnose and conduct repairs for this error code.

Parting Tips

When diagnosing for this error code, make sure you verify the failure and codes before you start to conduct any repairs.

It is crucial to conduct a visual inspection and check the wiring and connections of the components.

Prevent misdiagnosis of good components by following the pinpoint steps test.

Replace components only as needed based on your thorough visual test or pinpoint tests.