The problem was in the vacuum switching valve, not the electrical connection. Once I replaced the valve with a new one, the check engine light disappeared. Funny thing is, the dash board was previously displaying TRC and VSC errors before but after replacing the above valve, all these errors disappeared; don't know how they were all connected.
Anyway, thanks to everyone who chimed in on various ways to troubleshoot the issue. Problem is now solved.
Tuesday, March 19th, 2019 AT 11:53 PM