Technical Description of OBD-II Trouble Code
The range/performance of the intake valve control solenoid circuit on Bank 2 is not within specifications.
What does that mean?
This diagnostic trouble code (DTC) is a generic powertrain code that applies to OBD-II equipped vehicles such as Toyota, VW, Ford, Dodge, Honda, Chevrolet, Hyundai, Audi, Acura, etc. The specific repair steps may vary depending on the model.
In vehicles with variable valve timing (VVT), the camshafts are controlled by hydraulic actuators that are fed by the engine oil system through control solenoids controlled by the engine control module/powertrain control module (ECM/PCM). The ECM/PCM has detected that the range of movement of the intake camshaft on Bank 2 is not within specifications or is not operating when commanded. Bank 2 refers to the side of the engine opposite from cylinder #1 – be sure to verify which side is correct according to the manufacturer’s specifications. The intake valve control solenoid is typically located on the intake manifold side of the cylinder head.
Note: This code may also be associated with codes P0081, P0082, or P0083 – if any of these codes exist, fix the solenoid problem before proceeding with diagnosing the circuit range/performance issue. This code is similar to codes P0026, P0027, and P0029.
Symptoms
Symptoms of a P0028 DTC may include:
Causes
Potential causes of a P0028 diagnostic trouble code may include:
Possible Solutions
Engine oil – Check the engine oil level to ensure that it is sufficient. Since the actuators work on oil pressure, the proper amount of oil is critical to ensure the proper operation of the VVT system. Dirty or contaminated fluid may cause buildup, which can lead to failure of the control solenoid or the camshaft actuator.
Control solenoid – The control solenoid for the camshaft can be checked for continuity using a Digital volt/ohm meter (DVOM) using the ohms function. Unplug the solenoid wiring harness connector and check the resistance of the solenoid with the (+) and (-) leads of the DVOM on each terminal. Ensure that the internal resistance is within the manufacturer’s specifications if available. If the resistance is within specifications, remove the control solenoid to verify that it is not contaminated or damaged, causing a loss of oil pressure.
Camshaft actuator – The camshaft actuator is a mechanical device controlled by internal spring pressure and adjusted by oil supplied by the control solenoid. When no oil pressure is supplied, it will default to a “safe” position. Refer to the manufacturer’s suggested procedure to remove the camshaft actuator from the engine’s camshaft to ensure that no leaks are present that would cause a loss of oil pressure to and from the actuator’s hydraulic supply/return feed lines or within the actuator itself. Check the timing chain/belt and components to ensure that they are in proper working order and installed in the correct position on the camshaft gear.
ECM/PCM – The ECM/PCM commands the control solenoid using a Pulse width modulated signal (PWM) to regulate the amount of on/off time, resulting in control of the pressure used to move the camshaft actuator. A graphing multimeter or oscilloscope tool is required to view the PWM signal to ensure the proper operation of the ECM/PCM. To check the PWM signal, tap the positive (+) lead into the ground side of the control solenoid (if supplied by constant voltage, ground controlled) or the powered side of the control solenoid (if permanently grounded, positive control), and attach the negative (-) lead to a good known ground. If the PWM signal is not consistent with changes in engine RPM, there may be a problem with the ECM/PCM.
