Hilux Cylinder Pressure Issue

Sounds like a consequential error, perhaps related to the timing belt. Have you checked the head gasket? If the timing is off, it can cause fluctuations. Kinda like a domino effect.

Head gasket seems okay, no milky oil or overheating. Is the timing belt issue you mentioned something I can check myself, or is it workshop territory?

Checking the timing belt's tension and alignment can be tricky without the right tools and knowledge. It's like trying to perform surgery with a butter knife. Best to get it checked professionally to avoid further damage.

Thanks for the advice. Turns out the problem was indeed caused by a loose wire that was causing all of the issues, so the garage did a basic repair. All good now, and the pressure is stable again!