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Pete, Technician
Category: Boat
Satisfied Customers: 29144
Experience:  17 years automotive training and experience.
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Marine Engine Mercruiser 8.2 year 2012 Catalyst Engine

Customer Question

Marine Engine
Mercruiser 8.2 year 2012 Catalyst Engine
Smartcraft alarm reporting Service OBD soon
Scroll thru screen, Message "Oxygen sensor not working properly"
is there a way I can troubleshoot and fix myself
Submitted: 1 year ago.
Category: Boat
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

I dont show the diagnostic procedure for this fault on this model here but in almost all cases when you have a faulty oxygen sensor code this indicates the sensor itself is at fault needing replaced.I have had to replace several faulty oxygen sensors in the past before for issues like this here and suspect yours needs replaced.Make sure there is no damaged wiring or connections to the sensor needing repaired or replaced.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
Hi Pete:Thanks , there are four oxygen sensors on this mercruiser 8.2 Catalyst equipped engine.
Is there a way to tell which oxygen sensor is faulty?
Expert:  Pete replied 1 year ago.

Are there any code numbers coming up on the screen with this message at all?

Customer: replied 1 year ago.
it is a defective O2 sensor out of 4.
Can you advise if there is a way for me to test the functionality of each individual 02 sensor?Please advise.
thank you.
Expert:  Pete replied 1 year ago.

You should have a signal wire on each sensor that should fluctuate usually around 200 millivolt to around 900 millivolt when warmed up.If you have a cat or filter on the exhaust and there are two sensors after the filter or cat. then the signals on these should remain steady with slight movement on their signal wire when warmed up as well.If one is not moving like the others this usually indicates a faulty sensor needing replaced.

Unfortunately I do not have a diagram on this model to tell which wire is the signal wire.

Let me know if you need anything else and feel free to rate my help here as this is how I receive credit for my time.

Thanks Pete