How does the oxygen sensor work in a catalytic converter?
The catalyst efficiency monitor verifies that the catalytic converter is operating at a high enough efficiency rating to keep exhaust emissions within predetermined values. The PCM compares the signals from the upstream and downstream oxygen sensors to determine the state of the converter. These “tests” are called the readiness monitors.
What should the voltage of an O2 sensor be?
In other words, if the oxygen content is low it produces a high voltage (0.90 Volts – Rich mixture) and if the oxygen content is high it produces a low voltage (0.10 Volts – Lean mixture). Although theoretically the O2 sensor should cycle between 0.00 volts and 1.00 volts, in reality it cycles between 0.10 volts and 0.90 volts.
How does a post catalyst sensor read fuel content?
The post-catalyst sensor does not suffer this problem because most of the excess fuel and oxygen is consumed in the catalyst. It will read an accurate mixture, usually, but not necessarily, a voltage of 0.5 volts or higher. A standard oxygen sensor measures neither oxygen nor fuel content in exhaust gasses.
Why are the oxygen sensors after the cat?
Also post catalyst oxygen sensor is after the cat not before… A misfire in which the fuel injector injects a mixture that is too lean to ignite will result in both oxygen sensors seeing a lean mixture. This will result in the sensor output of little or no voltage.
What should the voltage be on the oxygen sensor?
Testing (O2) Oxygen Sensor Voltage Signals Start the engine and check the sensor voltage signals on your voltmeter. The sensor voltage should cycle or fluctuate within the 100 mV-900 mV (0.10 to 0.90V) range. Hence, This means the sensor is operating properly.
Where is the O2 sensor on a catalytic converter?
Go to the drop-down menu bar at the lower left corner of the Waveform Library window and select, Oxygen / O2/ Lambda sensor. A lambda sensor is also referred to as an Oxygen or O 2 sensor, or a Heated Exhaust Gas Oxygen (HEGO) sensor, and plays a very important role in control of exhaust emissions on a catalytic-equipped vehicle.
The post-catalyst sensor does not suffer this problem because most of the excess fuel and oxygen is consumed in the catalyst. It will read an accurate mixture, usually, but not necessarily, a voltage of 0.5 volts or higher. A standard oxygen sensor measures neither oxygen nor fuel content in exhaust gasses.
What are the characteristics of a pre catalytic converter sensor?
These known good waveforms have the following characteristics: The pre catalytic converter sensor signal Channel A periodically switches between around 0.1 V (indicating a lean mixture) and 0.8 V (indicating a rich mixture). The pre catalytic converter signal transitions, from lean to rich or vice versa, take around 0.5 s.
The oxygen sensor and air-fuel ratio sensor in modern vehicles monitor the efficiency of the catalytic converter by tracking the gas levels in the exhaust.
What are the symptoms of a bad catalytic converter?
Symptoms of a Bad or Failing Catalytic Converter. 1 1. Reduced Engine Performance. One of the first symptoms commonly associated with a bad or failing catalytic converter is a reduction in engine 2 2. Rattling Noise. 3 3. Sulfur Smell from Exhaust. 4 4. Check Engine Light Comes On. 5 5. Failed Emissions Test.
Why does my catalytic converter smell like sulfur?
Sulfur Smell from Exhaust During engine combustion, sulfur-containing gasoline becomes hydrogen sulfide. A properly working catalytic converter will convert hydrogen sulfide into odorless sulfur dioxide. When failing, you may notice a sulfuric, rotten egg-like smell coming from the exhaust.
Where are the oxygen sensors on a Lexus?
The Lexus will have a bank 1 and a bank 2 O2 sensor: one is near the firewall and in front of the catalytic converter; the other is behind the converter closer to the rear. They should primarily be the same part, just different lengths of wiring. The bulb part is connected to the exhaust. Figure 1. Location of the oxygen sensors.
What to do if your Lexus has a P0420 code?
Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0420 code is combined with other codes, try fixing the other codes first. The cost to diagnose the P0420 LEXUS code is 1.0 hour of labor.
What does P0420 mean on a catalytic converter?
As the code description implies the P0420 code means that the vehicle’s control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting).
How much does it cost to diagnose a Lexus code?
The cost to diagnose the P0420 LEXUS code is 1.0 hour of labor. The auto repair’s diagnosis time and labor rates vary by location, vehicle’s make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour. How much do you know about cars? When is the code detected?
What happens when the O2 sensor drops off?
If the signal from the downstream O2 sensor continues to mirror that from the upstream oxygen sensor (s), it means converter efficiency has dropped off and the converter isn’t cleaning up the pollutants in the exhaust. This will set a fault code and turn on the Check Engine light when the OBD II catalyst monitor runs.
Can a faulty O2 sensor cause a converter to fail?
Faulty O2 sensors can lead to converter efficiency failure, too. One of the things a lot of technicians neglect to check is probably the easiest thing to check — the O2 sensor connections. The connector not only is the supply for the voltage and grounds, but the source of the needed air supply to the zirconium sensor.
Why is the rear O2 sensor behind the light-off catalyst lazy?
The O2 sensor behind the light-off catalyst (the Downstream Sensor) is also monitoring oxygen, but if the light-off (NOx) catalyst is storing oxygen properly (meaning the catalyst is healthy), the rear O2 sensor signal will be very lazy when compared to the upstream O2.
The catalyst efficiency monitor verifies that the catalytic converter is operating at a high enough efficiency rating to keep exhaust emissions within predetermined values. The PCM compares the signals from the upstream and downstream oxygen sensors to determine the state of the converter. These “tests” are called the readiness monitors.
Faulty O2 sensors can lead to converter efficiency failure, too. One of the things a lot of technicians neglect to check is probably the easiest thing to check — the O2 sensor connections. The connector not only is the supply for the voltage and grounds, but the source of the needed air supply to the zirconium sensor.
The O2 sensor behind the light-off catalyst (the Downstream Sensor) is also monitoring oxygen, but if the light-off (NOx) catalyst is storing oxygen properly (meaning the catalyst is healthy), the rear O2 sensor signal will be very lazy when compared to the upstream O2.
What does the O2 sensor on the ECM do?
The O2 sensor between the engine and the light-off catalyst “brick” (that’s the Upstream Sensor) monitors the oxygen level in the exhaust and the ECM/PCM uses that input for Fuel Trim adjustments. That Upstream O2 signal switches very rapidly in response to Fuel Trim (several times a second).