Tell us what it is doing. We will tell you what is likely wrong.

Describe the problem in your own words or answer a few questions. You get a ranked list of likely causes with the reasoning behind each one, how urgent it is, roughly what it costs, and a summary you can hand to a garage.

Knowing the vehicle changes the answer. Age, fuel and gearbox all move which faults are likely.

You can start without the vehicle details and add them later — the answer is just a bit less specific.