I hear ya and I hate that catch-phrase too, but really, the kind of sensation that's analogous to a "check engine light" is likely to be only moderately painful. Knee twinges letting you know to roll out your IT bands. Angina. Etc. The kind of thing that says "your body is still driveable but you need to fix something." Pain from fatigued muscles in the last stages of a race or a hard interval is often more uncomfortable than those important, niggling little signs of injury.

I think what you're calling "true pain" is more like those big red exclamation points on your dashboard, followed by bizarre noises and a stalled engine.