A dirty or clogged fuel filter will stop a modern turbo-diesel engine dead in its tracks. In fact, it’s one of the first things a switched-on mechanic will check on vehicles like yours. So if the mechanic has changed the filter and restored to car to full health, then I reckon he or she has probably nailed the cause and fixed it very simply and cheaply for you.

Let’s be honest; there are literally thousands of things that could go wrong that might make your vehicle stop. Modern cars are very complex things, but you need to have faith that sometimes, simple problems occur and can be fixed simply.

Running on after the ignition is switched off is more of a problem in petrol engines than diesels. But you haven’t told me which engine your Triton has, so maybe it’s the 2.4-litre petrol we’re dealing with here. If so, you may find that the running-on is being caused by poorly timed ignition which could suggest a problem with the physical bits that make up the ignition system, or even a problem with the computer that controls it all. Worn or leaking fuel injectors could also cause this problem.

If your engine is the turbo-diesel, then another potential cause of running on is a worn or stretched timing chain (the petrol engine uses a toothed timing belt which shouldn’t stretch) that has allowed the camshaft to get slightly out of phase with the crankshaft. In both these cases, the fault could easily be enough to trigger the check-engine light and keep it on to alert you to the problem. Have the vehicle scanned to see if there’s an ignition fault or what’s called a camshaft deviation, indicating a worn timing chain.

This is a pretty well-known problem with this model. The problem seems to be caused by a gear selector problem which gets worse over time as wear occurs. Jumping out of gear is also linked to a second problem of noisy engagement (grinding) of the first three gears.

Mitsubishi has developed a transmission repair kit which includes reinforced gear selectors and synchronisers. But it’s a pretty big job to fit and requires the transmission to be removed and disassembled. You could try Mitsubishi Australia’s customer service division to see if there’s any financial assistance in either obtaining or fitting this kit.