2002 ford focus automatic zetec

i was driving today and the light came on (orange light with a exclamation mark)bottom left hand side of the dash board.

i have a cheap dtc reader whcih brought up a h20 sensor (oxogen sensor on the exhaust)

i have also noticed that the main blowers in the car (hot and cold) only work when on full position 4 and not on anyothers.

i have ordered a new sensor for the exhaust and also a new resistor pack for the heater.

would the above faults with the car cause the diangsotic light to come on because my dtc reader only flagged up one which was the exhaust p0141 or something along them lines?