Tiburon L4-2.0L (1999)
Oxygen Sensor: Description and Operation
OXYGEN SENSOR
The Engine Control Module (ECM) uses oxygen sensor signals to maintain the air fuel mixture at the ratio resulting in optimum fuel economy and
reduced emissions. The amount of oxygen in the exhaust gases indicates, to the front oxygen sensor, whether the air fuel mixture being supplied to the
engine cylinders is rich or lean. The readings of the rear oxygen sensor are used to indicate the efficiency of the catalytic converter. The ECM calculates
catalytic convener efficiency by comparing the rear oxygen sensor signal to the front oxygen sensor signal. A normal oxygen sensor signal will
constantly fluctuate above and below 500 mV, with the front oxygen sensor signal frequency of at least 5 Hz at 2500 rpm. Due to the effect of the
catalytic converter, the rear oxygen sensor signal frequency will be lower than the front oxygen sensor signal frequency. If the rear oxygen sensor signal
coincides with the front oxygen sensor signal a large percentage of the time, this indicates a loss in efficiency of the catalytic converter or a malfunction
within the fuel system.
MANIFOLD CATALYST
The catalyst's efficiency is demonstrated in its ability to oxidize CO and HC emissions. The Engine Control Module (ECM) compares the output signals
of the front and rear oxygen sensors to determine whether the output of the rear sensor is beginning to match the output of the front oxygen sensor. As
the catalyst wears, the rear oxygen sensor's signal trace begins to match the front oxygen sensor's signal trace. That is because the catalyst becomes
saturated with oxygen and cannot use the oxygen to convert HC and CO into H20 and C02 with the same efficiency as when it was new. A completely
worn catalyst shows a 100% match between front and rear sensor outputs.
HEATED OXYGEN SENSOR
The heated oxygen senor senses the oxygen concentration in the exhaust gas and, converts it into a voltage which is sent to the ECM. The heated oxygen
sensor outputs about 800 mV when the air fuel ratio is richer than the theoretical ratio and outputs about 100 mV when the ratio is leaner (higher oxygen
concentration in exhaust gas.) The ECM controls the fuel injection ratio based on this signal so that the air fuel ratio is maintained at the theoretical ratio.
The oxygen sensor has a heater element which ensures the sensor performance during all driving condition.
