fault codes and performance

[art]

am i right in thinking when the st24/ contour develops a fault , the codes are logged on the ecu but do not show on the dash , and so a reader is required
if the battery is disconnected overnight will all codes clear from the ecu
also will certain codes put you into a safe map , or is it limp mode, and how will the engine perform in that case
thanks

 

[B3NN3TT]

Disconnecting the battery will eliminate the Check Engine Light, but will not clear the codes.

To clear codes, you need a code reader or scan tool of some kind.

The ECU runs the mix a little rich when there is a Check Engine Light.

 

[Smokinjoe]

The ECU runs the mix a little rich when there is a Check Engine Light.

I would think that would depend on the code. A cheapo code scanner can read and clear codes for you. In this world of OBDII, a cheap scanner is a must for any shady tree mechanic.

 

[B3NN3TT]

Since most codes are emissions-related, rich is safe. Extreme lean conditions cause detonation and catalyst damage.