USA regulators discovered in 2015 that that VW was using similar devices in 2015.
The Commission said Italy had failed to convince it that devices used to modulate emissions on Fiat Chrysler vehicles outside of narrow testing conditions were justified.
The case revolves around a type of diesel vehicle produced by FCA, an Italian-US company, which the German transport ministry said contained illegal software that made the auto appear cleaner in the official test than it was in actual road use - a so-called defeat device.
Italy has two months to respond to the Commission's request and may be eventually taken to the European Court of Justice if the answer is found to be unconvincing. If it fails to do so, it could face legal action from the EU.
The legal procedure could send the Italian government to court as the European Union cracks down on countries and automakers for the burgeoning scandal over diesel vehicle emissions; and for failure to accurately test and evaluate vehicle emissions overall in Europe.
Germany's Transport Ministry has asked the European Commission to investigate exhaust emissions of Fiat Chrysler vehicles for potential illegal manipulation devices, German government documents showed on Thursday (1 September).More news: Google challenges Apple's Siri by opening digital assistant to iPhone
Last December, the Commission launched cases against five nations, including Germany, Britain and Spain, for failing to police the auto industry adequately.
In March, the commission closed the mediation process, but without determining definitively whether the auto contained an illegal defeat device or not.
German authorities had detected indications of emission cheating in Fiat 550X, Fiat Doblo and Jeep Renegade diesel cars. The European Commission is monitoring the enforcement of these rules by and has already opened infringements against the member states that issued type approvals for Volkswagen Group in the EU despite the company's use of illegal defeat device software.
Last year, the Commission proposed an overhaul of rules on how vehicles are licensed and tested across the EU, but has faced resistance from member states and European Parliament.
The Commission's original proposal gives the executive new testing and enforcement powers, but does not pave the way for an European Union agency.