The Honda World Touring Car Championship team has withdrawn its appeal over Tiago Monteiro's exclusion from victory in the second Buriram race.
Monteiro had held off the Citroen of Sebastien Loeb to take victory in the twilight event, but his Civic failed a ride-height check after the race.
Honda launched an appeal as it was convinced the infraction was the result of damage sustained in the opening race, held an hour beforehand, causing the front splitter to fall lower during the course of the event.
But it announced on Friday that it was withdrawing the appeal because it could not provide adequate evidence to prove its case.
"In accordance with the FIA appeal process, the team sought legal advice in compiling evidence for their appeal," said a Honda statement.
"Despite evidence to prove the team provided full checks before the start of the second race, ensuring the car complied when leaving the grid (and the ground clearance was correct) the team were not able to provide sufficient proof as to how the fixing came loose over the course of the second race.
"Consequently, insufficient evidence would result in the appeal being rejected in court.
"Regrettably for this reason, and after consultation with Honda, the team thought it was more appropriate to withdraw the appeal in order to not waste valuable time of all parties involved."
The loss of the Thailand win dropped Monteiro from fifth to seventh in the 2015 WTCC standings, behind fellow Honda drivers Gabriele Tarquini and Norbert Michelisz.
The season finale takes place in Qatar next week