According to European regulators, it is too unclear for users of Google services how the company works.
With the search engine, for example, it is not always clear why Google ranks one results higher than the other, according to a study led by the Netherlands Authority for Consumers & Markets (ACM) and the Belgian Economic Inspectorate.
If the company does not change anything, fines may follow.
The Play Store for apps also often lacks information, say European consumer authorities that have investigated certain Google products.
A number of "points for improvement" emerged from this.
For example, the regulators believe that Google is not transparent enough about ranking results in its search engine.
For example, the company should make it clear to consumers whether certain brands or companies have paid for a higher position in the search results.
According to the regulators, essential information is sometimes missing in the Play Store, where the majority of people with an Android phone download apps.
For example, it is not always clear who the seller of a product in the app store is.
In addition, according to the ACM, Google does not always provide clear information about the terms of service for apps in the Play Store.
In its special search functions for hotels or flights, Google often fails to show prices including taxes or other necessary costs.
Supervisors threaten with fines
According to the regulators, with this opaque working method, Google does not properly comply with rules that are intended to protect consumers against deception.
If the American group does not implement the aforementioned changes, there will be a follow-up investigation, which may result in fines.
"Consumers must be able to assume that they are not being misled. The information they receive must be clear and complete," says ACM board member Cateautje Hijmans van den Bergh in an explanation.
"The choices they make should not be driven by false reviews or unclear paid rankings. Contact addresses should also be easy to find. In other words, consumers should be able to google with confidence."