About Dashboard warning lights: red, yellow and green: which statement is WRONG?
A blue dashboard light is a warning light, just like red and yellow.
A red warning light always means a serious malfunction (Book p.214); size or feeling does not matter.
The text explicitly states: do not keep driving longer than strictly necessary. 'Not immediately' is not 'never'; the problem still needs fixing soon.
/216 - only red means: serious malfunction, stop immediately and switch off the engine. Yellow does not require stopping immediately; you may continue, e.g. to the dealer, as long as not longer than strictly necessary.
Explanation
trap: outside-the-car colour association. Book p.212 - functioneringslampjes are green, yellow, or blue and only show which function is switched on; waarschuwingslampjes are red or yellow only. Blue never signals a malfunction