The ecm compares the two waveforms of the heated oxygen sensors located before and after the catalyst to determine whether or not the catalyst performance has deteriorated.
Air–fuel ratio feedback compensation keeps the waveform of the heated oxygen sensor in front of the catalyst alternates between back and forth, from rich to lean.
If the catalyst is functioning normally, the waveform of the heated oxygen sensor behind the catalyst switches back and forth between rich and lean much more slowly than the waveform of the heated oxygen sensor in front of the catalyst.
When both waveforms change at a similar rate, it indicates that the catalyst performance has deteriorated.
Monitor description
The vehicle is equipped with the two oxygen sensors (o2s). One is mounted upstream from the three–way catalytic (twc) converter (front heated oxygen sensor ”sensor 1” ), the second is mounted downstream (heated oxygen sensor ”sensor 2” ). The catalyst efficiency monitor compares the sensor 1 and 2 signals in order to calculate twc ability to store oxygen.
During normal operation, the twc stores and releases oxygen as needed. This results in low oxygen variations in the post twc exhaust stream as shown.
As the twc’s efficiency degrades, its ability to store oxygen is reduced. This causes higher variations in post twc exhaust stream oxygen content and results in increased sensor 2 signal activity as shown.
When running the monitor, the ecm compares sensor1 and sensor 2 signals over a specific time to determine the twc efficiency. The ecm begins by calculating the signal length for both sensors.
Monitor strategy
Typical enabling conditions
Typical malfunction thresholds
Component operating range
Monitor result (mode 06 data)
Refer for detailed information on checking monitor status.
Confirmation driving pattern
Hint
: if there is malfunction in the system, the waveform of ”sensor 2” (oxl2) may become a similar to the one of ”sensor1” (oxl1) shown in the diagram on the left.
Removal and installation of fuel control parts
Place for removing and installing of fuel system parts
work in a place with good air ventilation and without anything
flammable such as welder, grinder,
drill, electric motor or stove in the surroundings.
Never work in a place such as a pit or nearby a pit, as there is a ...
Rear collision preparation
Concept
The system reacts to vehicles approaching from
behind.
General information
Two radar sensors in the rear bumper monitor
the area behind the vehicle.
When a vehicle approaches from the rear at a
certain speed, the system responds as follows:
Active Protection: when a
collision seems to b ...
Coolant
General information
Coolant consists of water and additives.
Not all commercially available additives are suitable
for the vehicle. Information about suitable additives
is available from a dealer's service center
or another qualified service center or repair shop.
Safety information
Warning
With th ...