Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 12-19-2006, 11:41 PM
Registered User
 
Join Date: Jul 2000
Posts: 56
95 E320 DM code 2 & 26

My CEL has now come on twice over a several month period. Both times I have received DM codes 2 and 26. The 7 and 8 pins have no codes (1 flash).

Regarding code 26, I know for a fact that I have a defective upshift delay switch (worn diaphram). Being in a warm climate, I have chosen not to replace it at this time and have a BB placed in the vacuum line.

My question concerns code 2 (oxy. sensor). I replaced this sensor only 35,000 miles ago. Is it possible to be getting a "false" code 2 as a result of the defective upshift delay sensor or are these codes completely independent of one another?

Jack

Reply With Quote
  #2  
Old 12-20-2006, 08:19 AM
Moderator
 
Join Date: Mar 1999
Location: Tucker, Ga USA
Posts: 12,153
The 2 codes have nothing in common.

Code 2 almost always means a bad sensor. IF you had the fuel computer scanned & able to see live data from that computer you would have a better diagnosis.
__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator
Reply With Quote
  #3  
Old 12-20-2006, 10:27 AM
Registered User
 
Join Date: Aug 1999
Location: Florida / N.H.
Posts: 8,804
I have seen 02 sensor codes come up when either AIR or Trans delay have been BB'ed. Both of these systems are used to get the cat hot as fast as possible from cold start and when they are not working the 02 sensor can get carboned up. I have found a remedy is to do a 3rd gear, under load [ up-hill] hard run to clean the sensor.
try it.............
As DOC says, get an 02 sensor read out .
An easy DIYer test on these HFM units is to disconnect the 02 sig wire [ under passenger rug] . Hook your meter to it and with engine coolant up to temp, take the vac hose off the fuel regulator and plug the line so there is no vac. leak...meter should jump to Rich voltage b/c the fuel pressure is higher than normal with reg disconnected....next test, put that line back on and pull a convienient vac line and look for lean/low condition voltage. [ if you rapidly block this line on/off with your thumb , you will see the sensor voltage change with your on/off blockage,,this will tell you if the sensor is reacting fast.
What you are doing is manually causing the engine to run in both a rich and lean conditions and monitoring the 02 voltage to see if it reacts to your engines inputs. The reason for dis-connecting the 02 sig wire to the ECU is so the engine can not correct your manual inputs while making these test ..kinda like using the engine as a rich/lean condition generating tool............................
A scope is the best way to monitor a sensor, but for guys w/o such, this will give you some basic 02 sensor operation insight..

Last edited by Arthur Dalton; 12-20-2006 at 10:56 AM.
Reply With Quote
  #4  
Old 12-21-2006, 12:44 AM
Registered User
 
Join Date: Jul 2000
Posts: 56
Thanks MB Doc and Arthur for the input. Since I don't have a scope I'll try the 3rd gear remedy first and follow up with Arthur's DIY test if necessary. Will post results in a couple of weeks.

Thanks again.
Reply With Quote
  #5  
Old 01-13-2007, 12:25 PM
Registered User
 
Join Date: Jul 2000
Posts: 56
Follow up. Arthur's DIY test indicated a bad O2. The sensor was very carboned. I'll keep my fingers crossed that if the CEL does come back on, it will just be code 26 that appears and not also code 2. Thanks for the help.
Jack

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

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 On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 09:37 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page