Gear damage message injectors.

Servus, and indeed my friend did something rather stupid. While he was on the highway he had his engine(diesel) turned off, at about 130 km/h. A real explanation why he didn’t and right after he turned it on again also came directly a message for a transmission damage. A week later he was now at Kia in the workshop and they told him that he had to renew his injectors. Now I wanted to know, since we both know very badly about cars only When he stopped the engine (like a honk) he left the gear on D. Hope for quick and helpful answers and also like to put him down for it. Mfg A Kia Optima on 2016 he has.