Cleaning O2 sensors

Discussion in 'Fuel Economy' started by jcp123, May 20, 2014.

  1. jcp123

    jcp123 Caliente!

    Been looking into cleaning my far as I know, they are original to the car and with 240k miles they have to have some deposits. What I noticed watching live data on the UG is that the car seems to be insisting on a relatively rich trim. Long trims run about +5 to +7, but short terms seem to run between -2 and +4. They never exceed + 10 or - 10, which is good, but the sum of your long and short terms should be closer to zero.Would this help? Would I notice an increase in FE? I am sure it does the cat no good - maybe that's what has caused it to fail 18 months after I got a new one? Or does the Echo simply run a little rich?
    Last edited: May 20, 2014

    CPLTECH Well-Known Member

    It has been my understanding that over time the oxygen sensors get sluggish, their reaction time slows down, hence waste of fuel. If it were mine, a change was due a long time ago.
  3. jcp123

    jcp123 Caliente!

    Yeah I probably should change them...although on a car with a trade in value of roughly $800, I have a strict "southern engineering" policy lol. O2s are remarkably expensive for this car.
  4. RedylC94

    RedylC94 Well-Known Member

    Does cleaning them stand a good chance of being effective?
  5. jcp123

    jcp123 Caliente!

    I have found a good number of O2 sensor cleaning how-tos. Meaning, maybe a 50-50 chance at it being effective. Even with my discount, new O2s are 1/4 of what the car is worth.

    So far, I have rigged every issue I have had with the car. I cleaned the MAF, did my oil change with free oil (10w40, eh) but a good (Wix) filter, tried to clean my dead IAC with little effect (though now that it has warmed up it seems to try working again). I use the tire on the spare wheel because the original wheel is bent beyond balancing. The car gets great gas mileage, but it is a vehicle with 240k miles and a lot of abuse before then. Hell, I am the one who replaced the original, factory spark plugs at 190k miles if that gives any indication. It has none of the exterior trim remaining, lots of dents, scrapes, and dings, is missing a sun visor, and has no rear speakers. The drivers front fender is primer and has an aftermarket headlight assembly due to a collision. The front bumper is mostly held on with zip ties. The lower and upper engine covers are missing, the latter of which causes problems with water in the no. 1 spark plug tube, nearest where the belt slings water upwards/ The rear seat cushion's two outboard retainers have broken meaning it sits curled up on the ends. The front passenger door will not open unless someone on the inside pulls up on the door lock while the handle is pulled. AM/FM works, but not the cassette or CD player. None of the trunk carpeting trim is there anymore, and the carpet inside the car looks moldy. The passenger rear door frame has hit something up top and bent that part of the frame away from the body, so water leaks in. The fuel gauge doesn't move until 1/3 of the tank has been consumed, and empty happens about a needle width under the 1/4 tank mark. When I trump the car's reliability, it is because it has been beat hard and still starts, drives, and gives excellent FE. Factory alternator, power steering, cooling system, and suspension are all in good working order. Still has all four factory ignition coils. Factory timing chain is still in place, and Toyota says it lasts the life of the car. All sensors are factory original. Hell, even the a/c still works. There are no loose or weathered plastics inside. The seats have no rips or tears. It passes inspection and I would drive it cross-country at the drop of a hat. I am struggling financially and probably wouldn't put the money in that the car needs even if I could. It is worth almost as much rolling across the scales as it is to try and sell it. Since its core mechanicals are still sound, I try to maintain it the redneck way.
    Last edited: May 25, 2014
    Mendel Leisk likes this.
  6. vangonebuy

    vangonebuy Well-Known Member

    At 80,000 miles. My 05 chrysler van was getting really poor mileage.
    Had no error codes. And ran fine.

    Found a O2 test procedure online.
    Start / Shut down.
    Start / Rev engine to 1500 rpm. In park.
    Put in Drive at idle. Rev again holding brake.
    Back in park.
    Turn on A/C full blast.
    REPEAT test.

    When I was done. THERE WAS an new error code. O2 sensor out of range.
    On my van, When it goes out of spec. The computer reverts to its best guess range.
    Online, Read that it's common for the O2 to still work and not throw out a error code.
    As it ranges in and out of spec.
    That's where my was mileage dropping.

    The lower O2 rarely goes bad.
    The top O2 is usually the culprit.

    EZ replacement for me. But the slotted socket made it less likely to damage the wire.
    I remember it improved mileage. 1 - 2mpg. And being very happy with the results.
    $80 part for me. $8 socket.

    I never thought of cleaning it.
    But many online note to buy a good quality part. Not the cheapest.
  7. jcp123

    jcp123 Caliente!

    Is that specific to your van or a general test? The only test I had run into was to use an ohmmeter and measure resistance. But that wouldn't tell if an O2 is dirty.
    Last edited: May 31, 2014
  8. 08EscapeHybrid

    08EscapeHybrid Moderator

    I can understand your wanting to clean the sensors. I once put an aftermarket O2 sensor in my 1981 Buick, and I had awful problems. I ended up ponying up the cash to get the OEM sensor from the dealer. A couple years ago I had contemplated replacing all 4 of the O2 sensors in my 98 K1500, just because of age and mileage. The dealer estimate was close to $2,000. I declined having that service done.
    Last edited: Jun 2, 2014
  9. vangonebuy

    vangonebuy Well-Known Member

    I got the procedure off a Chrysler forum.
    Cant guarantee it will work for any other manufacturer.
    But, it certainly wont hurt anything.

    I found my original post on it. Slight different procedure.

    Start the engine.
    Idle it.
    Than race it about 2500 rpms for 5-10 sec's.
    Idle it again.
    Put on the A/C high and the high beams.
    Put the van in each gear:p, R,N,D,1,2.etc.
    Return the engine to Park
    Turn off the A/C.
    Shut it down.
    Now run the OBDII code test.

    Check for error codes.
  10. The Doctor

    The Doctor Old Dude, New Car


    They aren't Dirty.....they are contaminated by additives in the fuel, so they will run the engine richer and richer the longer you leave them in the car.

    I worked with an Engineer at CAT, who was testing O2 sensors.
    He told me that a brand new 02 Sensor would actually run a car a little on the lean side, but as it ages it will cause the car's engine to run Richer. At that time 60k was the max breakover point, when the sensors should be changed for peak performance.
    But in those days, I could get O2 sensors for about $25 ea. That no longer seems to be the case.

    I've traded off my last two cars at under 65k, and I've not changed an 02 sensor in a long time. I hope I never have to.

    Good Luck!
    The Doctor :cool:
  11. jcp123

    jcp123 Caliente!

    Interesting. I presume the CAT guy was mostly experienced with diesels? If so, does that carry over to gasoline engines?

    Otherwise I am seeing exactly what you describe. My long terms have richened alarmingly since I posted this. Long terms are often hanging out at +11 now as the rich-biased short terms are staying the same.

    I think I will pull the plugs and read them soon. I will bet they are a brown colour vs. a cleaner grey.

    As to cost, they are around $70 each for Bosch sensors with my employee discount. Rock Auto has fantastic deals...OE Densos are mid-50s, I can get close out ones for $26 from Beck/Arnley, but as I'd rather not cheap out on parts, I am torn...$50-something for two sensors as a temporary measure almost makes it worth it since this car is really showing it's age.

    But man, it is just against my nature to get cheap parts...
    Last edited: Jun 12, 2014
  12. The Doctor

    The Doctor Old Dude, New Car

    May I?
    I worked in the research labs at Caterpillar Tractor Co. some years ago. I worked with an engineer that was running tests on GM O2 Sensors.
    He gave me two of the free samples from GM to put in my Chevy X11, w/ high output V6 engine. At about 80k miles, the new sensors gave me almost a 20% increase in performance, and MPG. It was VERY noticeable.

    As he explained it to me, impurities in the fuel, that cannot burn, contaminate the elements in the O2 sensor and cause the car to run richer and richer, wasting fuel and impeding performance. The sensors don't just get coated like a spark plug can, but they actually change their properties so they send incorrect status to the ECC.

    The real fix is to just change the Sensor.

    On several cars since then, I've changed my O2 sensors and got a real jump in performance. Ah, the good ol' days, when we didn't worry about MPG, just the performance.

    Cheers Mates!
    Doc :cool:
  13. RoadWarrior222

    RoadWarrior222 rockit serjun

    In most of the older car forums I have hung out in, Bosch sensors aren't regarded as the "good" ones, the Nippon Denso, or NGK are more highly regarded. Closeouts of old stock from Rock Auto, should be of identical quality (Possibly better in some cases, if old made in west stock, vs new made in asia stock) to the same brand new, you just don't get the warranty.

    I have also heard from these that cleaning the O2 sensor can be achieved by burning off deposits from it with a blue flame on a blow torch. Not too-too hot, but you don't want orange flame at the torch because that's an incomplete burn and adding to the problem, you might see orange at the O2 sensor as some stuff burns off though.
  14. jcp123

    jcp123 Caliente!

    Bosch should be OK on anything but early/mid-2000s and later Chryslers which seem to REQUIRE an NTK (NGK's O.E. Division) from the dealer.

    I think I am going to replace rather than clean the O2 at this point.

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