Contents
What does high O2 voltage mean?
The high voltage condition from the O2 sensor is indicating a lack of oxygen in the exhaust or other related problems, such as a leaking fuel injector or a broken up catalyst inside.
How does the O2 sensor indicate a rich condition?
The oxygen sensor measures the amount of oxygen in the exhaust that is used in the combustion process. For pre-catalytic converter oxygen sensors used for fuel control: Less oxygen than optimal in the exhaust results in a signal voltage over 450 mV. This reflects a RICH CONDITION.
What causes high fuel trim at idle?
During idle when the throttle plate is closed, the vacuum in the intake manifold is high and very little air flow is entering the engine, so even a small amount of un-metered air will have an effect on fuel trim. This forces the PCM to react to the lean condition with positive valued fuel trim readings.
What causes high fuel trims at idle?
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.
What is the LTFT reading on my PC?
I found something yesterday and now the STFT are reading +3% but the LTFT is still up in the +28%. Do I need to take it for some drive cycles for the PCM to re-learn the new trims? Any help appreciated.
Where is the O2 sensor on the B2S2?
An aftermarket sensor was installed once again under warranty. The O2 sensor voltage readings did not change, so our diagnostic tech requested voltage readings on the command (ground) side of the B2S2 wiring.
How many miles does a van O2 sensor have?
The van has a 6.0L engine and had about 60,000 miles on the odometer at that time. The tech who was assigned the job replaced both rear O2 sensors. I don’t know his reason for doing this, as it happened to be my day off. The invoice stated “check code P0138 – O2 Sensor Circuit High Voltage (B1S2).”