What is O2 sensor simulator?
The OBD-II cars (1996-1998) have the two O2 sensors to measure the amount of oxygen in the exhaust gas. First sensor is measuring it right after gases escape engine and this data is used to adjust fuel trim of the engine, as well as catch some faulty conditions. The second sensor is located after the catalytic converter, and is used to detect the health of catalytic converter. The ECU expects the signal from the sensor to be oscillating from below 0.4v to above 0.6v, but not above 1.2v, every few seconds when cruising. If you install the after market downpipes with no cat (which as we all know is purely for off-road applications) the ECU will detect this and indicate the error (MIL). The ECU is quite lazy at detection, and detects this condition approximately during second long trip. You can reset the ECU to clear the error code, but it’s very inconvenient, as you don’t really know if the error was because of oxygen sensor or some important thing is wrong and needs to be taken care of
