The best way forward here is to take the car to a workshop that knows Audis and have them pressure test the cooling system. Modern cars have sealed coolant systems, suggesting that they shouldn’t lose any coolant at all. The reality is a little different, and what may have happened is that your coolant level has been falling very slowly perhaps over a period of years until the level is low enough to trigger the warning message.

By pressure testing the system, any leak should become visible and can be fixed. Water pumps, radiators, heat exchangers and the network of coolant plumbing that makes up a modern car can all develop leaks. Sometimes the leak is so small, the coolant evaporates before it ever hits the ground which is why there’s no tell-tale puddle under the car each morning.

Don’t automatically jump to the conclusion that your car has a blown head gasket; there are lots of ways for coolant to escape, which is why it’s wise to keep an eye on the level on a weekly basis.

The first thing to figure out is which version of the 2012 Q5 you have. See, in that year, Audi updated the Q5 and, in the interests of fuel saving, changed from a conventional hydraulic power-steering system to an electro-mechanical one. Each system has the potential to give problems, but for very different reasons. The change came in late 2012 (December) so your car is probably the earlier one, but a check of the build-plate will tell all.

In the case of normal power-steering, low fluid can cause the problems you've noted and is also likely to make the power steering noisy when you turn the wheel. In the electro-mechanical system, the fault could be with the electric motor that powers the steering assistance. In both cases, wear in the actual steering rack can cause the same symptoms. Either way, it needs to be checked by a specialist, as a car's steering is obviously a crucial system.

But before you do that, have the car's wheel alignment checked at a tyre shop. A car that is out of whack can sometimes exhibit very strange steering characteristics. And what about the absolute basics? When did you last check your tyre pressures? Low tyre pressure can also make the steering heavier than it should be. And it doesn't matter that you haven't had a flat tyre for years; tyres lose about one psi per month, just sitting in the driveway. That's why they need to be pressure-checked every few weeks.

This is an example of why you really shouldn't ignore warning lights as they flash up on your dashboard. In the case of the dual-clutch Audi transmission you have, the warning light indicates that there's a problem inside the transmission (often that the clutch-packs have overheated). Continuing to use the vehicle normally is not recommended as the transmission requires attention to prevent this overheating occurring again and causing permanent damage to the unit.

Audi certainly knew it had a problem with these transmissions back in the day and often the root cause was traced back to the mechatronics unit (the brain that controls the gearbox's clutches and selectors) and in many cases these units were replaced.

However, the chances of Audi attending to your problem now after many years of ignoring the warnings seems a bit remote. You might be lucky and discover that the warning is something as simple as a faulty sensor, but if there's damage inside the transmission, this won't be a cheap fix. Have the vehicle scanned and see what the transmission has been trying to tell you all these years. By the way, Audi's response at the time was in the form of a service bulletin, not a recall.