When I am driving my 2014 Kia Rio, the RPM needle will stop working then the engine will die. What could be the problem?

Failing or fluctuating needles on a car’s dashboard are often a symptom of a poor earth somewhere in the wiring loom. But the fact that the engine dies whenever this random symptom occurs suggests that there’s something a little deeper going on electrically. The tachometer needle could even be a red herring of sorts; going out in sympathy with the engine which has suddenly quit.

For that reason, you really need to have the car electronically scanned to see if it throws up any fault codes that can lead you to the problem component. It’s likely there’s a bad connection somewhere or a sensor that is suffering a slow death and giving these intermittent faults which stop the engine in its tracks. Without every sensor (and there can be dozens of them) working properly, a modern engine has no hope of functioning properly.

It's also worth mentioning that, in 2015, Kia issued a service bulletin for this particular Rio, examples of which had been illuminating their check-engine light and recording fault codes. The fix was to reprogram the ECU (the computer that controls the engine) so that’s would be worth checking, too. A Kia dealer should be able to identify cars that have had this fix.