Escort L4-122 2.0L SOHC (1997)
Oxygen Sensor: Description and Operation
Heated Oxygen Sensor (HO2S)
UPSTREAM OXYGEN SENSOR
PURPOSE
The Heated Oxygen Sensor (HO2S) detects the presence of oxygen in the exhaust and produces a variable voltage according to the amount of
oxygen detected.
OPERATION
A high concentration of oxygen, lean Air / Fuel (AF) ratio in the exhaust produces a low voltage signal less than 0.4 volt. A low concentration of
oxygen, "rich AF ratio" produces a high voltage signal greater than .6 volt.
The HO2S provides feedback to the Powertrain Control Module (PCM)indicating AF ratio in order to achieve a near stoichiometric AF ratio of
14.7:1 during closed loop engine operation. This HO2S generates a voltage between O.0 and 1.1 volts.
DOWNSTREAM OXYGEN SENSOR
