BERLIN (AP) — German public broadcaster ZDF reports that trucking companies in Europe may be using electronic equipment to commit large-scale emissions fraud.

Tests commissioned by ZDF and freight industry organization Camion Pro found that one in five diesel trucks operated by Eastern European firms had suspicious emission levels.

Experts at the University of Heidelberg concluded that the trucks were pumping out up to 14,000 metric tons of additional nitrogen oxide and evading millions in road toll fees.

In a program airing Tuesday, ZDF claims that trucking firms may be using gadgets to fool on-board computers into thinking the driver has used a diesel exhaust fluid, known as AdBlue.

AdBlue can significantly reduce emissions but represents an additional cost for the competitive freight transportation industry.