If an electronically controlled fuel injection engine equipped with exhaust oxygen sensors experiences faults such as unstable idle, weak acceleration, increased fuel consumption, and excessive exhaust emissions during operation, and there are no other faults in the fuel supply and ignition devices, it is highly likely that there is a problem with the oxygen sensor and related circuits.
Most engine electronic control systems have a self check function. When there is a malfunction in the oxygen sensor or related parts, the computer will automatically record the fault content. Maintenance personnel only need to use a dedicated decoder to read out the fault code to identify the problem. But what if there is no dedicated equipment? Here are a few methods to quickly check the quality of the oxygen sensor.
If it is suspected that faults such as unstable idle or poor acceleration are caused by the oxygen sensor, simply unplug the oxygen sensor connector during maintenance. If the engine fault disappears, it indicates that the oxygen sensor is damaged and must be replaced. If the engine fault persists, the cause should also be found from other sources.
The quality of the oxygen sensor can also be checked using a high impedance voltmeter. Connect the voltmeter in parallel to the output terminal of the oxygen sensor. Under normal circumstances, the voltage should vary between 0-1V, with a median value of around 500mV. If the output voltage remains at a certain value for a long time without any change, it indicates that the oxygen sensor has been damaged.
In fact, an oxygen sensor is a fairly durable component that can be used for 3 years or longer as long as the fuel quality is up to standard. The abnormal damage of oxygen sensors is mostly caused by excessive lead content in the fuel. It is necessary for drivers of cars equipped with three-way catalytic converters to pay attention to this point