How do I reset the service engine soon light on my 2002 Pontiac Grand

@erichall this works for most 1997 and up GM "F" and "W" body cars:

Remove battery POSITIVE cable.

Take ignition to full on/start position and hold for minimum of 1 minute.

Take ignition back to off. However, key will not return to off and will be stuck due to lack of battery power.

Reconnect battery positive. Various relays will chatter.

Now take key forward then back to off. It should now remove.

Re-insert key and start engine. SES should be off unless a Class "A" DTC error code immediately triggers it.

This resets any and and all DTC error codes stored and WILL clear a SES light. If it doesn't work then you will need a odb-ii scanner with reset.

Remember that there is a reason why the light came on in the first place. I would suggest that you get the OBD scanned to see what is going on with it.