Twice, once at the one year service and now, again at year 3 service, my car now has its engine management light on.

It went it in the best of health. Just a regular service. Now though the engine management says that the air pressure sensor in the induction manifold has failed.

This happened after the first service, they changed the sensor and it failed again. They then decided it had been overfilled with oil and the sensor contaminated. A good clean and it was fine.

Now the very same sensor has failed. During the service. They say it isn't their fault and are also saying that Fiat doesn't give three year warranties. The third year is aftercare and the repair is at Fiat's discretion.

I jolly well expect them to fix it and it will never see that main dealer again.

I'm only worried that my other Fiat has another two years to run on its warranty. So two more services with that garage.

Very unhappy.

Sounds crap. Don't think you have to go main dealer to retain the warranty. Right to repair?

https://www.theaa.com/driving-advice/service-repair/right-to-repair-campaign

Having never owned a car under warranty i wouldn't know...

This should also apply to the fiat garage but i guess your not sure about the word correctly in this sentence...

The work can be carried out by an independent garage as long as that garage uses manufacturer approved parts and correctly follows the manufacturer's service schedule.