O2 sensor problems

On my other blog I recently wrote a post about testing oxygen sensors. My view on the subject is that this is an often replaced in error part. Just because the code sets in the computer does not mean that the exhaust stream sensor should be replaced.

What I left out of the story and wanted to cover here was that sometimes the emission part simply does need to be replaced. For one thing they will not last forever and if your vehicle has 200,000 miles on it and still has the original part it may be time to replace it for maintenance.

But there is also a situation when the car emission part will definitely need to be replaced. And this is known as oxygen sensor contamination. This is when the emission component is destroyed by a problem with the vehicle.

Many things can cause an oxygen sensor to become contaminated. Before simply replacing a contaminated exhaust sensor find out why it happened. You can begin by examining the engine for problems. Fluids that leak internally in the engine such as coolant or engine oil that is seeping in the combustion chamber can plug the pores of the oxygen sensor and cause it to respond slowly or inaccurately.

If I pull out an oxygen sensor that is contaminated I will usually check into it with my bore scope and insert it into the hole where the sensor is mounted. This is a quick way to check for fluid other than water which is naturally occurring in the exhaust system.

But since most people do not have a bore scope you may have to disassemble the exhaust before the oxygen sensor that was having a problem and shine a flashlight in there to see if there is any oil or coolant present. If you find any of these fluids you have a bigger problem than a bad oxygen sensor.

What else can cause O2 sensor problems? There is one other thing that can cause a contaminated exhaust stream sensor. RTV which is the automotive term for silicone caulk and stands for room temperature vulcanizing is not good for the health of the sensor. This type of contamination is most common after a previous repair to solve some type of external leak.

When you are replacing oxygen sensors that have been contaminated you will see a build up around the louvered areas of the probe or tip of the part. This is where exhaust is supposed to flow freely for sampling.

The color and smell of the part may also indicate the problem or at least send you in the right direction. If the tip of the probe has a sweet smell this is a strong sign that it has been contaminated by engine coolant. If it smells burnt or has a black or brownish sludge like coding then this is a sign that oil has been entering the exhaust system.

As mentioned above if it is a silicone contamination this will usually leave white deposits on the exhaust sensor tip. Whenever you run into a contaminated sensor you really should replace it. I have never been successful at cleaning and reinstalling the component.

Visit the homepage for this blog about auto repair. There you will find not only the latest posts but you can browse through them by reading a brief excerpt. If you are looking for a mechanic to answer your questions about your own oxygen sensor problems visit this next link for some car repair help.