I've got an LSU4.2 lambda sensor (wideband) here that is covered in carbon deposits. It's visible on the outside, so it's probably also present on the inside. The holes aren't blocked yet though, but the reading i get seems to be a little off sometimes, and it reponds slow to transients. I use the Innovate LM-2 to read the sensor. I did free air calibrate it recently.

Now I was wondering what is the best but responsible method to clean it?
A vast range of solvents is adviced on the internet; vinegar, coca cola, carburetor cleaner, WD-40, gasoline, or special 'carbon cleaner' solvents. Others say to just give it a job with the wire brush. Some say the only way is to set your engine lean, and burn away the deposits by making a sportive trip.

As far as i know the inside of the sensor, the ZrO2 and the pump membrane are fragile and easily contaminated. I wouldn't want to go and break it by using a agressive solvent or other unresponsible cleaning method. Soo.. Anyone who knows a good and responsible way to clean it? If you know one, i'd like to ask you to explain why it wouldn't damage the sensor.

Cheers (as far as i could find, there's no duplicate but feel free to point me to it :)

2 Answers 2


I honestly don't think this is possible, at least without causing more harm than improvement. Solvents are right out. Without a mechanical action on the core beneath the perforated sheild, there's no motivation for the smaller stuff to leave.

The only thing I'd be willing to try would be an ultrasonic cleaner with mild dishwashing detergent.

Set your car lean and burn it away?? Seems terribly risky for a sensor that costs maybe $100. The LS4.2 prices (even Bosch sensors in general) have come down quite a bit, now that wide-band is being used more and more.

And that's probably Sensor 2, downstream, so running lean is sure to take more value and life OUT of your cat than you would add to the sensor. And frankly, if it is a downstream sensor, who cares if you aren't setting a code? Very few vehicles use post-cat information to change fuel trims. But maybe you have a BMW or Audi or some such that does this.

I use an LS4.2 in my Saabaru 92X post-turbo to provide information to a digital AFR meter. And it gets carbon on it, and I can't imagine how hot that gets post-turbo. I don't think you want to see those temps go through your cat.

  • Oh it's just a sensor i had lying around. I tried to make use of it as tailpipe analyzer for my oldtimer. So i also don't have a cat.(yay!) I've got electronics to read it out manually, and i made probe out of a steel pipe that i screwed the sensor in, to put in the tail pipe. It's just that the sensor is rather dirty. They cost around €40 on AliExpress, but cleaning it may be worth the effort. Ultrasonic cleaning sounds good(actually it doesn't haha) but i don't have access to such a device. Thanks anyway.
    – Bart
    Dec 7, 2016 at 8:07

You can use a propane torch to heat the tip of the sensor cherry red. Use a vice or adjustable wrench to hold the sensor by the nut and it will act as a heat-sink. Afterwards, the gunk will have turned to fine ash.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .