1999 ML320 O2 Sensor - Mercedes-Benz Forum
 
LinkBack Thread Tools Display Modes
#1 (permalink) Old 08-28-2010, 07:57 AM
BenzWorld Newbie
 
Date registered: Aug 2010
Vehicle: 1999 ML320
Posts: 1
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
(Thread Starter)
1999 ML320 O2 Sensor

My girlfriend and I share a 99 ML320 that has a number of cosmetic defects but one big problem, it can't pass the state emissions test. We just moved to Arizona in May and the check engine light was on when we moved so we knew we were going to have problems. A mechanic where we used to live ran a diagnostic and told us that both 02 sensors after the catalytic conveters were bad and it would be 400 bucks plus two and a half hours of labor to fix.

When we got out to Arizona we got ourselves a 90 day extension after failing the emissions test and have since been to another mechanic who has run diagnostics several times. The first time he told us the rear 02 sensors were bad and it would be 600 dollars. The second time he told us it would be 1100 dollars because now a third 02 sensor was bad and to reduce labor cost he may as well replace the 4th one. The third time we went to him was after I took a look under the car and found that the rear driver side 02 sensor was unplugged. We took it back for a diagnosis and were told only the rear two 02 sensors were bad.

I've since talked to several mechanic friends and they've all said the hardest part is getting under the car and getting the 02 sensors off but if I go to a mechanic I'll surely be wasting hundreds of dollars (which I can't afford anyway).

After doing some looking around online I have two real big issues standing between me and doing this myself:

1) How do I know only the rear two 02 sensors are bad if the front 02 sensor reported as good after i plugged in the rear 02 sensor?

2) How do I know ANY 02 sensor is bad if only the rear are throwing up codes? Can the diagnostic distinguish between bad 02 sensors and an actual 02 problem in the exhaust?

Further details: The mechanic here in Arizona has used a laptop program with multiple Mercedes logos (though that proves little) to run both "quick" and "full" diagnostic tests. Each time the only faults have been bad brake pads (replaced) and the 02 sensors.

ALSO: How do I find the chasis # / model code? (have seen some things about x 02 sensor only works with x + chasis or - x chasis and except model code 808 / 809 respectively)

Any assistance would be great! Thank you!
Centhryth33 is offline  
Sponsored Links
Advertisement
 
#2 (permalink) Old 08-28-2010, 11:48 AM
BenzWorld Elite
 
Date registered: Jul 2006
Vehicle: 1999 E55, 2001 E320, 1990 560 SEC, 2004 ML350, 2001 ML55, 1995 S500, 1998 SL500, 2010 E550 Sport zoo
Location: NW Arkansas, La Jolla CA, Hong Kong
Posts: 6,204
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 7 Post(s)
Honestly, the parts are like $180 for the (2) Bosch that are plug n play, slightly less for the universal type that get spliced in:

Your Parts Search Returned 0 Part(s) System&gid=5132@Oxygen Sensor

Any general shop can do that for you on a lift, just takes a lift and a little and the right tool - like 20 real minutes - not big labor dollars at all unless I am missing something here.

Keep the beat !
fabbrisd1 is offline  
#3 (permalink) Old 08-28-2010, 02:46 PM
Moderator
 
Date registered: Jul 2005
Vehicle: 90 300E, 99 ML430, 00 ML320, 05 E500 4matic Wagon
Location: WI
Posts: 14,277
Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 50 Post(s)
Lifetime Premium Member
And to answer the other question the scan tools can differentiate all 4 O2 sensors.
Noodles is offline  
#4 (permalink) Old 08-29-2010, 12:28 PM
BenzWorld Member
 
Date registered: Dec 2006
Vehicle: 1999 ML320
Location: NC
Posts: 273
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Yeah, autohausaz.com for the O2 sensors. Just go to autozone and have them read the codes, search those codes on this forum. It's probably a simple fix, and assuming the truck has a decent amount of miles on it with original o2 sensors, then that's probably the only problem. You can never rule out that something upstream is causing the failure though, so keep that in mind.
Dan P is offline  
#5 (permalink) Old 08-30-2010, 11:20 AM
BenzWorld Member
 
Date registered: Jun 2008
Vehicle: 1999 ML320
Location: Chicago, IL
Posts: 51
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I had the almost the same exact problem w/ my 99'. Failed the Illinois smog test, read the codes with my innova scanner and retrieved four post-cat O2 related codes (I forget exactly what they are, they're posted all over benzworld). I did a little research and purchased the sensors from autohausaz. I found step by step instruction here as well. Although I had a little difficulty removing the old sensors I got it after a little persuasion. Keep in mind, the car wasn't lifted at all. After replacing the sensors I drove for about 2 days to let all of the monitors reset, took to the testing site and PASSED. I've been up and running flawlessly for 4 months without issue. I'm almost at 200K
rpesnaux is offline  
#6 (permalink) Old 08-31-2010, 01:23 AM
BenzWorld Elite
 
macdrone's Avatar
 
Date registered: Nov 2006
Vehicle: 1993 400E 23100 miles "Gunter", 1999 ML320 200000 miles "Fizgig"
Location: Silverdale, Wa
Posts: 2,387
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Also on these rigs the cats are prone to failure which can throw a rear O2 sensor code. I have replaced my drivers side and now have to do the ppassenger side as the "brick" has broke loose and is rattling in the cat.
macdrone is offline  
#7 (permalink) Old 08-31-2010, 05:15 PM
BenzWorld Elite
 
Michael Pillay's Avatar
 
Date registered: Oct 2003
Vehicle: 2001 E55 AMG, 2001 ML320, 1984 500SE AMG
Location: Swartz Creek, MI
Posts: 4,705
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I would do the following. Get the specific codes. Advance Auto or Autozone can read them for you. The codes will tell you which O2 sensor(s) to change. Order the new sensor(s) from autohausaz. Once you get the sensors. Get under your M class. Make sure that you do this when it is completely cold. Exhaust systems get HOT. Locate your O2 sensors. There will be one before and one after each of the catalytic converters-that makes a total of 4 but you will only be changing the ones that threw a code. Unplug the electrical connector for the sensor. If I remember correctly there is a bracket that holds part of the sensor wiring or something in place. Unbolt the bracket. To undo the O2 sensor itself there is a special tool. I had no need for one. The right size wrench worked fine. Reinstall the new sensor and reattach the bracket. It should not take long.

Mike
Michael Pillay is offline  
Reply

  Mercedes-Benz Forum > Mercedes-Benz Vans/Trucks/SUV/Others > W163 M-Class


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
User Tag List

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Topic Author Forum Replies Last Post
1999 ml320 temp sensor bigmoo W163 M-Class 4 08-08-2012 05:39 AM
1999 ML320 Brake Pad Sensor light FixMyBenz W163 M-Class 2 12-03-2005 06:49 AM
1999 ML320 Value pize98 W163 M-Class 4 11-18-2005 12:07 PM
1999 ML320 vs. 1999 RX300, which is better ? mbeclass W163 M-Class 8 08-09-2004 06:06 PM
New (to me) 1999 ML320 Dr Stewart Ginsberg W163 M-Class 1 01-26-2002 07:22 PM

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome