Navara Diesel Power Loss

A check engine light, power loss, and increased fuel consumption on a diesel Navara often point to fuel delivery or timing issues. Fluctuating cylinder pressure is a symptom, not the root cause. Has the timing belt ever been changed? At that mileage, it might be due. Alternatively, consider getting your injectors checked, as faulty injectors can cause uneven cylinder pressure. Any unusual engine knocking sounds?

I haven't changed the timing belt since I bought the truck, so it's probably overdue. There's been a slight rumble, especially when accelerating. Could a bad timing belt cause all these problems at once? And if the timing is off, could that damage the camshaft or head gasket?

That rumble plus the other symptoms REALLY points to the timing belt. A worn or slipping timing belt can absolutely cause those issues. The 'rumble' you're hearing could be the engine struggling as the timing is off, leading to uneven combustion. If the belt goes completely, it can cause catastrophic engine damage. STOP driving it immediately! Get it towed to a workshop. Continuing to drive it could cost you thousands.

I took it to the workshop, and you were spot on – timing was off! Apparently it was a consequential error stemming from low oil pressure. They reset everything and the whole repair was covered by my warranty. Feeling like I dodged a bullet.