2000 S80 T6 - Yesterday the engine light came on and would not go away after shut off and restart. Today I disconnected the battery for a few minutes and reconnected.
I drove for 30 miles and notice the warning triagle light come on for a few seconds with message of fuel cap not on or something to that affect and went back off, the engine light did not come back on. Any thoughts on what could cause this and is this something that would cause an emissions test failure? I will need this test done next month.

Last year I spent $600 to replace 2 o2 sensors before I could pass this test.
At the time the engine light stayed on before replacing the sensors.

Thanks