Can a water pump go bad with no check engine light?

That was exactly the question when we first learned of that code. The manual says right out that code does not light up the MIL.

The over-revolution probably means the impeller has split and now can spin too fast because it isn't moving much water.

 

... or if the first year of Gen 3 had the P148F code ...

 

Per the link above, it first showed up in the 2011 repair manual.

 

If the impeller is broken, it's not turning or turning but not moving the coolant.
But the magnetic part "is" turning, if it's broken from the plastic impellor.

 

Can separate where it's bonded together, like this:




Then the pump motor tends to spin too fast (because it's not really moving much water, so it is not working as hard). In a 2011 or later you can see the P148F code, but in 2010 nobody had thought they would need a code for "pump runs too fast".

 

Usually if you command the pump on with tech or the software you can actually hear the pump struggling to try and run because the impeller plastic has frayed and is rubbing the housing or the impeller is spinning and not turning with the rest of the assembly etc You can actually hear this It makes the sound of a struggling electric motor that's having trouble making a complete rotation so you get all that funny noise then when you unbolt it and remove the black liner piece between the pump body and the engine then you see the impeller and what's really happening A lot of nothing.

 

When our water pump failed we had no CEL. The red over temp warning light turned on and I quickly parked it until it cooled off. Then, I added some distilled water and nursed it home without the light returning. 10k miles later the head gasket failed at cylinder #2 at only 125k miles.

 

It might be over speeding for a quick second, but 10/10 times we pull one with this code they are completely or almost completely seized up.

 

Well done. Thanks for coming back to report what you found on the water pump. Hopefully, you changed it in time before damage was done to the head gasket. Only milage and time will tell.