o2 sensor bad? no codes is this possible?
i have obd1 which unlike obd2 doesnt constantly read the o2 sensor. It determines a sensor being bad by checking to see if it stays lean or rich for a full 30 seconds and if it passes this test then the computer thinks the sensor is good. My question is i got 5 mpg less than i should which can be caused by a bad 02 sensor, can my o2 sensor on the right side be bad and the computer not know it?