What does it mean?
OBD II fault code P0029 is defined as “Exhaust Valve Control Solenoid Circuit Range/Performance (Bank 2)”, with “Bank 2” denoting the side of the engine opposite that contains cylinder #1 on engines with two cylinder heads. Code P0029 is set when the PCM (Powertrain Control Module) detects a fault in the electro-hydraulic control system of the VVT (Variable Valve Timing), or VCS (Variable Camshaft System).
The code setting parameter is generally a voltage variation that exceeds 10% of the reference voltage for the exhaust camshaft actuator for that particular application. Consult the relevant manual for the exact value of the voltage variation that will set code P0029 for the application being worked on. VVT and VCS systems use pressurized engine oil to act on actuators that control variable valve timing.
The PCM gathers information from various sensors regarding engine speed, engine load, throttle position, and others to calculate an appropriate valve timing setting to increase power, and/or improve fuel economy. Since the engine oil is the agent that transfers power to the actuator that ultimately controls the exhaust valve timing, it should be obvious that oil of the correct type, viscosity, and cleanliness is crucially important to ensure the proper functioning of these systems.
The image below shows a typical VVT control solenoid.