[updated:LAST EDITED ON 22-Oct-02 AT 00:27 AM (EST)]>Use electrical motor cleaner (found in auto stores). Spray
>some in a small container and soak the end of the sensor.
First of all. It's not whether it can or can't be cleaned. Anything can be cleaned, if you go about it right. The question should be, first of all, whether cleaning it would do any good, and if so, whether it needs to be cleaned. Oxygen sensors are exposed to such extreme heat that the only thing that it can get (dirty) with is carbon. Extreme heat will turn any organic matter, such as gasoline or oil, into carbon. Well the bad thing about that, is that baked carbon is not soluble in any kind of solvent, and even if it was, the sensing unit within the o2 sensor module, is not exposed, and is not visible. It is covered by what is usually a louvered steel cylinder. Therefor if you're going to brush it, use a wire brush and brush it as hard as you want, because it isn't going to hurt the steel cover. But this is the problem. The only thing that you can really clean with any success is the outer cover. Since solvents won't do any good, I really would not recomend using electric motor cleaner, since the active indredient in it is Trichloroethylene which is not a very strong solvent. not only is it's strength very low, but also, since it is designed to clean electronic components, it evaporates very rapidly, resulting in a very short working time.
Since o2 sensors are disigned to hande such extreme temeratures. The best method of cleaning them, is to heat the bottom part of the sensor (the part that inserts into the exaust) with a propane torch, to the point that it just begins to turn red. You do not want it to glow chery red, even though they are designed to take extreme heat, you can still over do it. Once you have it heated to the point that is just turns red, or to the point just befor it turns red, quench it in water. This will break free any carbon build up inside the sensor. After the first time, some pieces may still be to big to come out of the sensor so I would recomend doing it 2 to 3 times, blowing it out with an air compressor between each time. But I would have to say, good luck, since O2 sensors very seldom fail do to being dirty. This is not common at all.
It is generally not a good idea to use water to clean O2 sensors, unless you can live with killing it.
Sudden cooling hot Sensors (heat-tempering) also runs the risk of cracking them. The sensor uses ceramic components. These components are more durable than the ceramic you'd expect to find on your sparkplugs, but still they're just colored glass.
Imagine what would happen to a Sparkplug's ceramic jacket if heated, then dropped in water .
Cleaning is not a bad idea, but it's difficult to get it clean enough to make any difference. Try blowing loose soot out with compressed air. Solvent might work, or might move the soot further into the sensor and deposit it there when the solvent evaporates. Your solution might be to use both (wear protective eye gear!)
not true, even baked on carbon can be clean off, go to your local autozone, and there is a product called Deep Creep by Sea Foam, it's a intake cleaning, and multi purpose lubricatant, that is sensor safe ( better than WD40 i think) i sprayed a little on a EGR valve and all the baked carbon fell off in like 3 minutes
However, as stated, even if you get it clean, there are no guarantees that it will restore the sensors accuracy. The only way you can do that is to replace the sensor itself. And remember, there are other expensive components that depend on that O2 sensor working properly. Some of these components are the catalytic converters (if the sensor fails, the converter have to deal with the elevated fuel levels and/or elevated heat), but the engine can also be damaged by rich operation over an extended time. It is much cheaper to replace the sensor with a new one, than to attempt to clean a dirty sensor, call it good and end up replacing cats down the road. Its an easy choice, replace a sensor, or replace a sensor, catalytic converters, clean the engine, and waste money on the cleaners you used to clean the sensor after spending X amount of time wasting fuel because the sensor was so far off.
Sooner or later you are going to get stuck with replacing the sensor.
Some additional things to consider.
The threads on the sensor are only good for so many times in and out. Even if you use a good anti-seize, the repeated heating and cooling cycles eventually cause the sensor to go out of round. When you reuse the sensor, you take a good risk that it will get stuck in the port the second time. Now extracting it becomes a much bigger issue. When you replace the sensor, you get a clean set of threads.
Second issue, the heated part that extends into the engine is not the only part of the sensor that needs t be cleaned. The sensor allows air to enter near where the wires come in on the outside of the sensor. The sensor measures the O2 content of the exhaust relative to the ambient level. You cannot get to either the ambient part of the sensor, nor the exhaust part directly, as they are both shielded. So effectively cleaning them is very difficult if not impossible.
Another point to consider. If cleaning sensors was practical and cost effective, like it is with MAF sensors and many other things, then you would be able to purchase remanufactured O2 sensors. The fact that no remanufactured O2 sensors are available means that no one has figured out a way to fully restore an O2 sensor that is cheaper than just replacing it.
Most of you are incorrect about what to use on an OX sensor.
An OX sensor is based on a ceramic substrate and depends on oxygen "migration" through the substrate to generate a voltage for feedback to the PCM in proportion to what it finds in the exhaust flow.
It normally must operate at exhaust temperatures in excess of 600° to output it's intended varying voltage for the PCM to use.
Two major types of conditions could exist.
One, a crusting from combustion deposits as a result of what's in various gasolines.
Secondly, deposits from cylinders burning oil in the combustion mix, or coolant leaking into the combustion process or some other contaminant introduced through the intake.
For the crusting, heating tip area with a torch to burn off the deposits often will bring back sufficient operation as detected on a digital voltmeter monitoring the sensor output as the tip is heated to a dull red color.
Much of the time the tip has a metal guard over the sensor areas and you can't see the actual active area.
If some other contaminat is present like oil, the substrate may be block beyond cleaning by any method.
Attempts to clean with various cleaners may render a unit inoperable or slow laxy operation by blocking the substrate and you would never know this.
So the answer to the question of cleaning is, "it depends".
Don't use any cleaners. You are often warned not to introduce anything ahead of the sensors, not to use certain additives, lubes and greases, gasket sealers etc that may come in contact with the sensors.
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