Oxygen sensor fault diagnosis, from the following aspects:
First, the engine under the idle air idle operation, the engine ECU HT terminal voltage is about 12V. If there is no heating voltage, the oxygen sensor must work poorly.
Second, if the ECU HT terminal voltage is normal, then the next should check the oxygen sensor heating resistor is good or bad. Unplug the oxygen sensor wire connector, with a resistance meter to detect the oxygen sensor between the terminals 1 and 2 resistance, the resistance value should meet the standard value. General normal value of a few ohms, such as the resistance value of infinity or zero, then the resistance open or short circuit, you must replace the oxygen sensor.
Third, the engine in the high-speed operation, the engine ECU terminal OX voltage should be in the 0-1V jump state, such as a long time at 0V or 1V, may be oxygen sensor failure, it may be other parts of the engine failure. At this time we have to oxygen sensor to test the basic performance to distinguish between these possibilities. Test using an oscilloscope, there are two ways to increase the air method and increase the fuel method.