What would cause service engine light to come on and then go off?

Question

I had the scanner hooked up to it and it says its an oxygen sensor light, bank one sensor 2. It will stay on for several weeks, go off and then come back on for a while. What would make it go off and then back on like that??

Answer 1

About typical for a failing O2 sensor. As the sensor failure progresses the signal gradually drifts farther and farther from the expected reading, at times the reading will be normal, at other times it may be far out of range. If the sensor returns normal in range readings for 2 or more engine start cycles the light will go out until the sensor once again delivers an out of range reading.



Have the sensor replaced and if the tech is able to identify any other O2 sensors at the edge of normal readings have them changed also.

Replacing all questionable sensors at the same time will eliminate the likely hood of sequential failures - when the computer gets better readings from the new sensor it is likely to decide that the next worst one is bad, the technician's understanding of the relationships between the sensors will be key to preventing this scenario.

Answer 2

If the light on and off that mean the problems come in and off.If the problem is the o2 sensor that means this sensor some time work and some time not.After the problem detect by car computer then it will record in it and trigger the light on.If the problem gone after few cycles of drive]ing the computer will automatic erase the code and the LIGHT gone until next time problem come.What is exact the code number.Sometime it say oxygen sensor problem but actually not sensor is bad.For last 5-10 year O2 sensor are build very tough and not easy broken.If it pinpoint the sensor is bank 1 and second one that mean this sensor located after the CAT and no need to change other sensor and wast money.Don't make O2 sensor so complicate.It is a simple device just when oxygen pass through it and genera voltage from 0-1 Volta,if a lot of O2 will have 0 v no O2 will be 1 v.When the gas/air maxture is lean will have high O2 come out 0 V will come out. This data(voltage go to the computer and the computer base on the program we put it in to recact.the computer can't predict which sensor will be down.

Answer 3

The sensor is in the process of failing, the Computer runs test on the sensors (tests how many times it switches rich to lean in a certain amount of time...on most cars). Sometimes the car fails the test and turns the light on, sometimes it passes the test (usually has to pass twice for light to go off) and the light shuts off. I would bet a new o2 sensor fixes it, Good luck!