Final answer:
A consistently high O₂ sensor voltage typically indicates that the engine is running rich, meaning there is too much fuel in the air-to-fuel mixture. However, it could also suggest that the O₂ sensor is faulty.
Step-by-step explanation:
If the O₂ sensor voltage is always high, it typically indicates that the engine is running rich. This means there is too much fuel in the mixture and not enough oxygen.
When the sensor detects an excess of oxygen in the exhaust, it outputs a lower voltage. If the sensor consistently reads a high voltage, it signals that there is less oxygen present, pointing to a rich condition.
However, it’s also important to consider that a persistently high voltage could be indicative of a faulty O₂ sensor. In such a case, the sensor may not be responding correctly to the actual oxygen levels in the exhaust.
If the O₂ sensor voltage is always high, it indicates that the engine is running lean. The O₂ sensor measures the amount of oxygen in the exhaust gases, and a consistently high voltage suggests that there is less oxygen in the exhaust. This can be caused by a variety of factors, such as a vacuum leak, a malfunctioning fuel injector, or a clogged air filter.
Therefore, option 2 is the correct answer: The engine is running lean. When the engine runs lean, it means that there is a higher proportion of air and a lower proportion of fuel in the air-fuel mixture.
Options 1, 3, and 4 are incorrect because they do not align with what a consistently high O₂ sensor voltage indicates.