2008-2013 Cadillac CTS General Discussion Discussion, Check engine light reason in Cadillac CTS Second Generation Forum - 2008-2013; My check engine light came on this week while I was climbing a steep mountain in my '09 3.6 DI. ...
My check engine light came on this week while I was climbing a steep mountain in my '09 3.6 DI. The dealer says that the code indicates that my axillary water pump failed. I didn't know that I actually had an axillary water pump. Apparently it is electric and runs only when the standard cooling system can't handle the load. The dealer had to order one, of course.
Good Luck Steadfastrock. Mine has been on order for over 1 month. Called customer service, absolutely no help. No surprise there! I'm told it will be in sometime by mid August. The part may not be that big a deal but I hate driving around with my check engine light on. BTW. This is the second time it's needed to be replaced.
It looks more like a "bypass valve" than a motor. It appears to allow some water from the radiator outlet to bypass back into the top of the radiator. I'm refering to the device that is imediately back of the top of the radiator on the right side (passenger side). I would think it is there for a faster engine warmup in cold weather.