Luoyang, and Cen took this opportunity to submit a secret petition urging Emperor Taizong to reduce his travel out of the capital. He also pointed out that too many construction projects were being carried out on behalf of Emperor Taizong's favorite son, Li Tai (the Prince of Wei)—that such expenditures will breed further expenditures. Emperor Taizong was pleased with Cen's petitions and awarded him with silk. In 642, Cen was given the additional designation of Zhuanzhang Jimi (專掌機密)—considered a chancellor de facto designation. It was said that Cen was humble and, despite his honorable status, he always greeted those who had known, no matter how minor that person's position was. In 643, when Emperor Taizong's crown prince, Li Chengqian, was deposed after he was discovered to have plotted to overthrow his father, Cen and Liu Ji suggested that Emperor Taizong create Li Tai crown prince, but Emperor Taizong subsequently created another son, Li Zhi (the Prince of Jin) crown prince, believing that Li Tai's machinations was responsible for Li Chengqian's downfall. Emperor Taizong made many high-level officials carry additional titles as Li Zhi's staff members, but when he tried to bestow such a title on Cen, Cen declined, stating that he wanted to concentrate on serving the emperor, although Emperor Taizong still had the crown prince meet with Cen every five days and treat him as a friend, not as a subordinate. In 644, when Emperor Taizong, at an imperial gathering, stated to his key officials their strengths and weaknesses, he spoke, with regard to Cen: Cen Wenben is kind-hearted, and writes exquisitely. His logic and analysis are also enduring ones, and he will not fail my expectations. Later that year, he was made the head of the legislative bureau, but he rejected all attempts to congratulate him, stating "I will only receive condolences, not congratulations." When his mother asked why, he stated, "I did not have accomplishments and was not an old acquaintance of the emperor. I have, however, received great favors from the emperor, and my position is high and important. That is why I am afraid." When people suggested to him that he spend more time managing his properties, Cen responded: He instead put his younger brother, Cen Wenzhao (岑文昭), to be in charge of his properties. At that time, Cen Wenzhao was spending time associating with people, and Emperor Taizong was not pleased. He considered demoting