For 1990-2009 cars

Condition | Action
--- | ---
Low oil pressure | Insufficient or poor oil supply to valve train.

1. Perform oil pressure test.
2. Repair or replace all damaged components.

Improper lubrication to the valve finger-follower |

1. Inspect valve finger-follower, valve bridge, valve finger follower lifter, oil pump and engine block oil galleries.
2. Repair or replace all damaged components.

Worn or damaged valve finger-follower |

1. Inspect valve bridge and finger-follower.
2. Repair or replace all damaged components.

Sticking valve | Carbon on the valve stem or valve seat may cause the valve to stick.

1. Inspect valves and valve guides.
2. Repair or replace all damaged components.

Worn or faulty camshaft lobes |

1. Inspect camshaft lobes.
2. If damaged replace camshaft and all valve finger-followers.

Damaged or misaligned timing gears |

1. Inspect timing gears.
2. Replace all damaged components.