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Old 10-22-2001, 11:22 AM
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Oxygen Sensor - am I being ripped off?


My car failed emissions (high CO), also has a cold running problem (runs rough/hesitates/stalls when cold). Took it to the dealer, the guy charged me 1.5 hrs of diagnostics, then says that the O2 sensor is not responding, needs to be changed, and only then he can do further testing. Quoted $170 for the sensor, $15 for the lambda tower (does it always have to be replaced with the sensor) plus 1.5 hours of labor (@ $72 per hour, it comes to nearly $300 just for replacing the O2 sensor!!).

Am I being ripped off by the dealer on the O2 sensor? I thought it was a $50 part, and takes 15 minutes to change.

Would really appreciate any responses / past experiences (Steve, MB DOC, what is the MB flat rate for this?)

Thanks a ton,

190E 2.3 (85, 121K)
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Old 10-22-2001, 12:17 PM
Registered User
Join Date: Jul 1999
Location: Youngstown, OH
Posts: 150

I would be a $50 part if it were installed in a ford but because the you need a plug that only fits a MBZ you are stuck! Unless, you buy one for another car with the same size mounting hole in the exhaust pipe and cut and solder in your old plug-ins. But $170 seems high... check on-line and see if your mechanic will come close. P.S. DON'T comprimise on quality here.

The tower is a different story. My mechanic just drilled mine out and left in open so he could always have access to it. Legally, Federal emmissions laws, it is ONLY supposed to be adjusted by the mechanic. So you really are stuck.

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Old 10-22-2001, 12:27 PM
G-Benz's Avatar
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Join Date: Apr 2001
Location: Dallas/Fort-Worth
Posts: 5,711
I toyed with the idea of replacing mine to cure a weird problem, and my sources show that the price is probably a little high.

Fastlane shows them to be less than $130, even lower than the list price, which is around $150, still $20 lower than the quote you got.

Dealer parts quotes are almost always higher than other sources, so unless I am buying a hard-to-obtain trim piece or MB antifreeze, I stay away from the MB parts counter...
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car
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Old 10-22-2001, 12:53 PM
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What about the labor - isn't 1.5 hours too much for it?

thanks for your responses anyway.

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Old 10-22-2001, 01:12 PM
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Join Date: Jan 2001
Location: Santa Clara, CA
Posts: 437
FYI, I found this reply on a thread entitled "Hard Cold Starting". By the way, the local dealer in San Jose now gets about $135/hour for labor, consider yourself lucky with only $72

coil fix
I found a thread on the coil problems with 190's and 300's nor really having a strong spark. ( neither here not there for arguement) what I am saying is, I had an old coil and a suspected ignition/coil problem. I followed the threads advice and got a Accel universal Hi output coil from mail order. Installed it in about an hour in original location and just replaces coil lead end. This not only fixed idle and start prob. but the engine runs better, uses less gas, and the coil with shipping cost under $60. I can supple the info I gathered in the installation on request. It has been in the car for 5000 miles and no problems whatsoever with compatability. Same with the o2 sensor swap I learned about on the site. 1990 Ford mustang sensor is the same output and input information...sensor costs only $37! Direct replace MB part. Works for 190 and 300, maybe more

Christopher Henkel
1990 190E 2.6
'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet
'86 560SL 124K Miles
'94 320E Wagon, 74K Miles-128K Miles JUNKED
'06 E350 Wagon, 84K Miles
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Old 10-22-2001, 03:17 PM
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
The O2 sensor part number is 006-542-96-17 & list is $162(check partsshop!!).
Takes about 15-30 minutes to replace, depending on rust!!
There are GENERIC O2 sensors that will work, this car uses a 3 wire sensor!
Diagnostic times vary due to many different items.
MOST cold running problems aren't related to the O2 sensor but to the coolant temperature sensor.
MERCEDES Benz Master Guild Technician (6 TIMES)
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Old 10-22-2001, 04:50 PM
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Another thing - does the lambda tower HAVE to be replaced with the O2 sensor? Intruder was saying something about Federal laws regarding tampering with it - should one leave it open so that other mechanics can access it? I guess what I don't understand is this - how does one adjust the fuel mixture if the tower is sealed (not that I am going to do it myself)?

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Old 10-22-2001, 05:18 PM
Registered User
Join Date: Apr 1999
Posts: 2,632
$170 for the O2-sensor of a 190E is outrageous.

Both Caliber Motors and Cutter Motors (Mercedes Dealers) charge about $130 for the 3-wire O2-sensor.

Even the 4-wire type for a 1995 C36 cost me only $140.

If you really want to save $$$, get a new 3-wire O2-sensor ($50)for a (1985-1990?) Ford Mustang 5.0, splice the connector off your old O2-sensor, and you've saved yourself almost $100.

I did this with our 1988 300TE and it worked fine.

Labor-time to replace is out of line. Find a reputable independent shop ASAP.

Check connections of the O2 sensor first.

Best of luck,

:-) neil
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Old 10-22-2001, 05:32 PM
Registered User
Join Date: Jun 2001
Location: California
Posts: 326

Take a look at this thread that discussed the lamda tower and adjustment:

O2 Sensor

I'm watching with interest because both of my cars barely passed the last smog test. Both were at the max limit for Hydrocarbons. The basic remedy is "replace the cat and the O2 sensor and you should be fine". Wow! That will sure add up!

I'm hoping that there is somebody out there who has installed a universal O2 sensor and can report back with their experience.

04 ML500
02 E430

Experience is something you don't get until just after you need it.
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Old 10-22-2001, 05:36 PM
Ali Al-Chalabi's Avatar
Senior Member
Join Date: Nov 2000
Location: Knoxville, TN
Posts: 1,837
I replaced the 3 wire sensor on my bimmer for under $60.

I bought a generic 3 wire Bosch sensor and spliced it in to the old connecter.

1.5 hours labor seems very very high.
Ali Al-Chalabi

2001 CLK55
1999 Dodge Ram 2500 Cummins Diesel
2002 Harley-Davidson Fatboy
Merlin Extralight w/ Campy Record
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Old 10-22-2001, 06:29 PM
David C Klasse's Avatar
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Join Date: Jan 2001
Location: Mission Hills in the City of San Diego
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I paid $175 from my dealer.
But had it installed at a private mechanic which only took about $20 minutes! This is for a C280.
2006 E350 w/ 155k miles (Daily Driver)

1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
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Old 10-22-2001, 06:37 PM
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Join Date: Apr 1999
Posts: 2,632
FWIW, my SMOG tech. and I do the following before any emissions testing. It requires some planning but not a lot.

1) run a full-tank of Chevron Supreme and a full-bottle of Techron;

2) 2-days before your test, change the oil & filter;

3) the day of the test, run your engine for a minimum of 20-25 minutes under load. If possible, do some wide-open accelerations up a long hill for 5-8 minutes;

4) if you SMOG test shop is NOT ready to test your car, ask them when they will be ready, because you want to be tested HOT (I will sometimes circle the block);

This has worked for my 1978 Dodge van, a friend's 1988 300E, and another friends 1989 Corvette. NONE were dyno tests, just a sniffer.

If you need to replace the CAT, I have been successful in using CATCO cats at about $80-$120 mail-order depending on application.

Good luck,
:-) neil
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Old 10-23-2001, 12:23 PM
Registered User
Join Date: Jul 1999
Location: Youngstown, OH
Posts: 150

The tower change is not a MUST unless the fuel:air ratio needs adjustment after the new O2 sensor is changed. I usually count on having to adjust it, which is why mine was drilled out and plugged up with a bolt for future access.

BTW, listen to MBDOC, since some of your problems are cold running problems and probably not O2 sensor related, check with another mechanic. It may be worth your while.

If you include the tower change, the time is probably right. I would not consider that a DIY'er. Not because of the difficulty but because of the risk of dropping something into the intake manifold.

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Old 10-23-2001, 05:45 PM
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Alright, I got my car back today. The guy changed the O2 sensor, but not the lamda tower. Said it now fluctuates between 40%-45%, that the O2 sensor is working nicely. The tech felt it should cure the cold running problem - said that since the sensor was shot, it was giving the full 12V signal during preheating, which could be driving the ECU totally crazy. Once hot, it was functioning on open loop anyway, which was set rich. Didn't do any mixture adjustments - said it was redundant since the O2 sensor would take care of it.

So that's that. I am not a tech guy, so there's not too much I can do myself, so gotto trust someone. I did get him to assure me that there would be no more diagnostic charges for this problem, if it doesn't get solved (they charged me 3 hours labor total!).

Lets see, I have my fingers crossed.

Thanks for all the responses. Will keep you posted on how it goes.

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Old 10-23-2001, 09:08 PM
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I say thats very high for what they want to charge you .But it sounds like you are kinda stuck between arock and a hard place .He already clipped you the 1.5 hrs diagnosis if you go else where at this point even to a place that may be a little less expensive it might still cost the same. That really erks me when they charge you for diagnosis and then tell you we first have to fix this problem to see if there are any more problems ***** if I knew you were gonna change parts till you find the problem I could do that myself and it weould be alot cheaper anyway thats my 2 cents oh do find a new independent repair shop that has a good reputation Goodluck
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