What is the voltage of a B2S2 sensor?
The tech compared voltage readings for both sensors using our scan tool. B1S2 showed 800mV and B2S2 showed 600mV. The tech substituted a light bulb to serve as a load across the B2S2 heater circuit terminals. With KOEO, the bulb did not light.
How is the sensor ground grounded to the engine?
The sensor ground is externally grounded to the engine, as well as to the ECU. The ECU is grounded to the engine also. We know that as the injector duty cycle increases, the average ground current of the ECU will also increase, and therefore so will the voltage drop between the ECU and the engine.
Why do ECUs have dedicated sensor ground wires?
This is why ECUs have dedicated sensor ground wires. If the sensor’s ground is not isolated from the body of the sensor and it has to screw onto the engine, for example many Nissan cam angle sensors, narrowband oxygen sensors and many knock sensors, then you don’t have a choice; you have to choose the star point ground at the engine.
What was the voltage reading on the O2 sensor?
The O2 sensor voltage readings did not change, so our diagnostic tech requested voltage readings on the command (ground) side of the B2S2 wiring. The test results showed .5V from the PCM on the command side of the circuit, which the diagnostic tech interpreted as the sensor heater being off.
How is the O2 sensor different from the two wire sensor?
This sensor is similar to the two wire design; the difference is that instead of using the body of the O2 sensor as a ground, the third wire is the ground, eliminating the potential of poor ground between the O2 sensor and the exhaust system making it more efficient.
This is why ECUs have dedicated sensor ground wires. If the sensor’s ground is not isolated from the body of the sensor and it has to screw onto the engine, for example many Nissan cam angle sensors, narrowband oxygen sensors and many knock sensors, then you don’t have a choice; you have to choose the star point ground at the engine.
The sensor ground is externally grounded to the engine, as well as to the ECU. The ECU is grounded to the engine also. We know that as the injector duty cycle increases, the average ground current of the ECU will also increase, and therefore so will the voltage drop between the ECU and the engine.
What causes a low O2 sensor voltage signal?
Excess oxygen in the form of regular ambient air will send the O2 sensor voltage signal low (under 0.450 volts) and lack of it will send the voltage signal high (over 0.450 volts). A stuck open EGR valve will create a lack of oxygen in the exhaust, since the re-circulating exhaust has all its oxygen already burnt.