How to diagnose 'check engine' light? - PeachParts Mercedes-Benz Forum

e430guy · #1 07-22-2006, 08:42 PM

I have to do a smog check on my '99 E430 in several weeks. The check engine light has been on for awhile and needs to be fixed. It used to be fixable by either adjusting the gas cap or rubbing vasoline on the cap gasket. I replaced the cap to no avail. Is there a port for the OBDII diagnostics I can plug into? Where is it located?

thx

#2 07-22-2006, 08:47 PM

the port is under a little cover above the drivers feet area? do you have an obd 2 scan tool? are you in san diego? i brought my generic scanner home from work i could try to scan it for you if you are close

e430guy · #3 07-23-2006, 03:54 PM

I found the port, went to AutoZone and scanned. 2 codes came up: P0170, & P0173, which refer to 'fuel trim malfunction', banks 1 & 2. I'm thinking this is the O2 sensors, but how to dianose from here?

#4 07-23-2006, 04:27 PM

Quote:

Originally Posted by e430guy

I found the port, went to AutoZone and scanned. 2 codes came up: P0170, & P0173, which refer to 'fuel trim malfunction', banks 1 & 2. I'm thinking this is the O2 sensors, but how to dianose from here?

with out proper diag hard to say, but normally when you see those codes it if from the airmass sensor, did it specify part load or at idle? if you do replace the airmass sensor be sure to do the filter as well

whunter · #5 07-23-2006, 04:42 PM

Best guess:
Breather hoses broken, loose or failing to seal..
This allows unregulated air to enter the system = P0173

Vehicle: 1999 Mercedes Benz E 430 Sedan
Part: Breather Hose
----------------------------------------------------
Breather Hose
Partial load
crankcase ventilation
-----------------------------------------------------
Breather Hose
Partial load
crankcase ventilation
-----------------------------------------------------
Breather Hose
Partial load
crankcase ventilation
-----------------------------------------------------
Breather Hose
Full load
crankcase ventilation

http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1US0YZ0AN1UU0Z62DB&year=1999&make=MB&model=E-430-001&category=B&part=Breather+Hose

e430guy · #6 07-23-2006, 05:06 PM

Breather hoses? Can you be more specific? That would be excellent if a hose would fix the problem.

Also- does anyone out there know what the correct part number is for the maf sensor? I found several sites on-line with Bosch parts, but the p/n are different. B3130-161380 and BSH074590

thx

e430guy · #7 07-23-2006, 05:08 PM

OK I finally saw the link on hoses but how to locate them on the car...