Cause
Water in fuel tank
Water in the fuel, from condensation, a leaking filler seal, or contaminated fuel taken on at a pump. On a diesel it is genuinely damaging rather than merely inconvenient, because the injection system depends on fuel for lubrication and water provides none — a slug of water through a high pressure pump can destroy it in one journey.
The symptoms are erratic and load-dependent. Water settles at the bottom of the tank and is picked up in slugs, so misfires, stumbles and pressure faults come and go with fuel level, cornering and gradient. A fault that worsens as the tank empties is the pattern, since the pickup sits where the water is.
Modern diesels carry a water-in-fuel sensor and a drain for exactly this, and a warning from it should be acted on rather than reset. Drain the filter bowl and look at what comes out — water separates visibly and the answer is immediate. Petrol engines tolerate small quantities but suffer corrosion and, in cold weather, ice in the lines; and a persistent problem in either fuel argues for a leaking filler seal rather than condensation.
Typically a moderate job.
Some of these codes mean you should stop driving
1 of the 3 codes this can cause indicate a fault where continuing to drive risks damage or is unsafe. Which one you have matters more than the cause does — read the code's own page before deciding.
Codes this can cause (3)
Codes where this is a likely explanation first, rather than merely a possible one.
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