S14 240sx, what is code 91?

[Just another 240]

Hi all,

I am currently living in the U.K, and one night the gas station went out of 90 octane gas(that's the highest they have on base) so i had to put something cheaper. About two days later? my check engine light came on when my car is warming up ( remotely start). I retrieved code 91 from the ecu today; I drove it around and the light didn't come back on, so thinking to myself that it was good to go. Later on in the evening, when i remotely start the car up again, the light came back on. I retrieved and erased code 91 again. I remotely start and turn off my car, the light did not come back on, it looks like it only comes on during a cold start maybe?

I looked into the Chilton and a site once given by a member from nico on how to read the codes and found nothing on code 91. The car drives and act normal. So does anybody know what's code 91? and yes i searched. Thank you.

[audtatious]

OBD-I code 91 is "Front Heated Oxygen Sensor".

[Just another 240]

thanks man