whatever you read in the book is complete ****e.
the engine management light and error message occur when the engine develops a fault.
There are 3 levels of fault.
a fault that generates a code but does not put the engine light on. these are low risk faults
a fault that generates a code that does put the engine light on. these are moderate risk
a fault that generates a code, puts the engine light on and puts the engine into limp mode, limiting power / revs. these are higher risk.
however the fault code you have could be relitively minor and could be informing you that something has gone wonky, it could simply be a sensor had an off moment, reported a dodgy value and gave a fault code, or you could actually have an error.
until you get the fault codes read you wont have a clue what has gone wrong. it should be safe enough to drive to the dealer but dont go far in it.
whatever it is, the ECU can only decide what is going on from the values given to it by the sensors, so it has to be something a sensor can read, so either it has read something out of the ordinary or the sensor is broken, making it think something is out of the ordinary.
1999 156 1.8TS Sport Pack 3
2001 166 3.0 V6 24V Super
2003 156 GTA 3.2 V6 24V
2005 156 1.9 JTDM-Jet Sport
2008 159 1.9 JTDM Lusso
1997 GTV 2.0TS Lusso
2001 147 1.6TS Lusso