A truck carrying a billboard was parked outside a building to catch the eye of top bosses of SM Entertainment.
Fans of EXO - managed by SM - are demanding that singer Chen, 27, be dropped from the South Korean boyband after he announced his marriage earlier this month.
The pressure tactic worked but in an unintended way - it caught the eye of the authorities who promptly towed away the truck over a parking violation.
The vehicle was meant to be stationed at the site till the end of the month.
According to the allkpop portal, members of a fan club, who paid for the billboard, were upset that Chen had not behaved like a gentleman, getting his girlfriend pregnant before their wedding.
They protested that his action had smeared the image of the group.
The news of the truck being towed away drew mirth from many netizens who said EXO fans should not interfere in Chen's private life and that the fan club had wasted money.
One person posted: "When you're spending your own money to make someone's life miserable just because they decided to get married, that money is better spent on therapy."