Variable Valve Timing (VCT) is a technology that Ford and other vehicle manufacturers use to alter camshaft timing for optimum performance, emissions and fuel economy. The VCT actuator mechanism on the end of the camshaft(s) uses engine oil pressure to advance or retard cam timing. How much cam timing is advanced or retarded depends on operating conditions and will vary with engine speed, load and other variables.
Oil pressure to each of the VCT actuators (one for each camshaft) is routed through a VCT solenoid (one for each actuator). The opening and closing of the VCT solenoids is controlled by the Powertrain Control Module (PCM) based on inputs from the engine's Cam Position (CMP) sensors, Throttle Position (TPS) sensor, Mass Airflow (MAF) sensor, Manifold Absolute Pressure (MAP) sensor, transmission gear range, vehicle speed and other inputs.
When a timing change is needed, the PCM commands the VCT solenoids to change position so oil pressure either flows to or is blocked from reaching the VCT actuators on the intake and/or exhaust camshafts. The PCM monitors the change in camshaft timing via feedback from the Cam Position sensors.
If a cam timing change does not occur when it is commanded by the PCM (no change in the relative position of one of the camshafts as reported by the cam position sensor), or if cam timing changes by the wrong amount (too much or too little), it will set one or more fault codes and turn on the Check Engine light.
Diagnostic Trouble Codes (DTCs) that often occur with Variable Cam Timing faults include:
P0011....A Camshaft Position Timing Over-Advanced or System Fault Bank 1
P0012....A Camshaft Position Timing Over-Retarded Bank 1
P0013....B Camshaft Position Actuator Circuit Bank 1
P0014....B Camshaft Position Timing Over-Advanced or System Fault Bank 1
P0015....B Camshaft Position Timing Over-Retarded Bank 1
P0016....Cam/Crankshaft Position Correlation Sensor A - Bank 1
P0017....Cam/Crankshaft Position Correlation Sensor B - Bank 1
P0018....Cam/Crankshaft Position Correlation Sensor A - Bank 2
P0019....Cam/Crankshaft Position Correlation Sensor B - Bank 2
P0020....A Camshaft Position Actuator Circuit Bank 2
P0021....A Camshaft Position Timing Over-Advanced or System Fault Bank 2
P0022....A Camshaft Position Timing Over-Retarded Bank 2
P0023....B Camshaft Position Actuator Circuit Bank 2
P0024....B Camshaft Position Timing Over-Advanced or System Fault Bank 2
P0025....B Camshaft Position Timing Over-Retarded Bank 2
P0026....Intake Valve-Bank 1 Control Solenoid CKT Range/Performance
P0027....Exhaust Valve-Bank1 Control Solenoid CKT Range/Performance
P0028....Intake Valve-Bank 2 Control Solenoid CKT Range/Performance
P0029....Exhaust Valve-Bank2 Control Solenoid CKT Range/Performance
A problem with the Variable Cam Timing system may cause the following symptoms:
A rough idle
Decreased fuel economy
Decreased power when accelerating hard
If you find a code that says one of the cams is over-advanced or over-retarded, the problem could be either a faulty VCT actuator on that cam, a bad VCT solenoid for that cam, or possibly a faulty wiring connection to the VCT solenoid.
The most common cause of VCT codes and problems is dirty oil. Varnish and gunk can build up inside the VCT solenoid(s) and/or VCT actuators, restricting or blocking the flow of oil through these parts. A plugged VCT solenoid may not allow enough oil pressure or any oil pressure to flow to the cam actuator, preventing the cam from changing time. Or, if the VCT solenoid is opening and closing properly, but the actuator is gummed up with gunk, the actuator may fail to change cam timing.
NOTE: Variable Cam Timing problems can also occur is an engine has low oil pressure. Low oil pressure can be caused by worn engine bearings, a worn oil pump, low oil level in the crankcase, or using a motor oil that is too thin (low viscosity rating) for the application. For more information on this subject, see Troubleshooting Low Oil Pressure.
The VCT solenoids are located on the engine's valve covers.
First, check the electrical connector to see if it is loose or corroded. If the connector is making good contact but the solenoid does not respond when energized (no click), the solenoid has failed and needs to be replaced.
A plugged solenoid may open and close when energized (it will click), but the internal screen inside the solenoid may be so plugged up with gunk that it may not allow any oil flow to the actuator (or not enough to make it change cam timing). You can remove and attempt to clean the solenoid by spraying solvent into the oil passageways, or soaking the solenoid in solvent. But they can be difficult to clean. The best advice is to replace the solenoid with a new one.
Important: If one or more VCT solenoids (or actuators) are plugged with gunk, change the oil and filter and change your oil more frequently to prevent the same problem from occurring again. Many experts recommend changing the oil and filter every 5,000 miles to prevent gunk from clogging the VCT actuators and solenoids.
Ford TSB 16-0038 was issued March 3, 2016 for vehicles that may be experiencing Variable Cam Timing problems. The bulletin covers the following vehicles with 3.5L turbocharged V6 engines:
2016 Ford Expedition
2016 F150 Pickup Trucks
2016 Lincoln Navigator
The above vehicles may have a Check Engine light illuminated with any of the following codes: P0011, P0015, P0016, P0017, P0018, P0019, P0021 and/or P0025.
If your Ford has codes P0011 and P0016, replace the bank 1 intake VCT solenoid.
If your Ford has codes P0015 and P0017, replace the bank 1 exhaust VCT solenoid.
If your Ford has codes P0018 and P0021, replace the bank 2 intake VCT solenoid.
If your Ford has codes P0019 and P0025, replace the bank 2 exhaust VCT solenoid.
The replacement VCT solenoids for the left side exhaust or right side intake are AT4Z-6M280-A.
The replacement VCT solenoid for the left side intake is AT4Z-6M280-B.
The replacement VCT solenoid for the right side exhaust cam is AT4Z-6M280-C.
Ford 4.6L, 5.0L and 5.4L V8 engines also have Variable Cam Timing, as do Ford 3.7L CNG/LPG V6 engines. Like the Ford applications listed in the above TSB, any of these engines can also experience similar problems. The higher the mileage on the engine, and the older the vehicle, the more likely one or more VCT solenoids and/or actuators may become clogged with gunk and varnish if you don't change your oil and filter regularly. Use a quality motor oil that meets Ford OEM specs when you change oil, and use a long life name brand filter.