If the Supreme Court's Criminal Division for Persons Holding Political Positions agrees with the EC's "red card", Mrs Leena will be disqualified as member of the National Reform Council (NRC).
She will not be able to run or vote in any election for five years.
The EC found some of her senator campaign posters deceptive. One of them was: "Scrap oil fund. Petrol to be 20 baht [a litre]. Vote for Leena Jungjanja No. 3 for Bangkok senator."
Another read: "Bring back PTT to Thai hands. Petrol to be 20 baht".
The EC said such promise was not a duty of a senator or within his or her authority.
It will send the case to the Supreme Court for further action.
Mrs Leena was on Thursday nominated to the NRC for laws and judicial process reforms. She ran under the banner of Maha Prachachon party.
The 2014 interim charter bans a person whose election right has been or used to be revoked to join the NRC, cabinet or National Legislative Council.