97 E320 Check Engine Light/OBD Codes
 

Scanned the codes and got 3 codes: P0170, P0130, and P0170. Don't know why P0170 came up twice. From the research, P0170 is most likely the mass air meter, and the p0130 is the oxygen sensor.

Questions:

I read some where that W210 E310 has two oxygen sensors, how do I tell which one failed?

Anybody know if the 10 year california emission warrenties on autos cover oxygen sensors.

Thanks

Marcus

Actually, the OBDII codes tell you..
 

Hi. PO130 is "O2 Sensor Circuit Malfunction, Bank 1, Sensor 1"
Sensor 1 is the sensor closest to the engine, before the cat.
PO170 is "Fuel Trim Malfunction". The fuel trim is set by the engine computer (ECM) above or below the factory mean by a small amount based on the feedback from the O2 sensor.
I'd replace the forward O2 sensor and clear the codes. I'm guessing the bad sensor is causing both codes.
If one of the techs is reading, and I've got this wrong, please leap in.
Sorry, can't help with your last question.
Hope this helps, KenP

additional info:

checked with 1 800- mercedes and was told that mass air flow sensor is covered in california for 7 yrs and 70,000 miles. So for my 97 E320, it's covered.

also, the P1030 code that I got was a "pending" code, I think it means that it detected a malfunction, but has not trigger the check engine light. The check engine light was most likely caused by the air flow sensor (P0170) code. What do you experts think?

Another question for the experts: How do I convince the dealers that the P0170 code is really the mass air sensor failure? If I can convince the dealer, I can get it replaced under warranty.

Thanks for all the help.

Marcus (a mercedes DIY newbie with a new code scanner)

OBD codes are standardized so you will never convince the dealer that P0170 is the MAS, cause it is not, MAS codes are P0100 to P0104.

Thanks for the info inspector1.

I searched the forum, and most of the P0170 code seems to trace to the air mass flow sensor. So, if P0170 is not air mass sensor, what is it?

See this link:

http://www.whnet.com/4x4/mb-dtc.txt

Other MB tech (stevebfl) stated in other post that this may be caused by a loose purge valve.

Thanks for the replies.

Lets see if I can make sense of what I am thinking:

P0170 is the Fuel Trim Bank 1, ie. O2 sensor is not manageing the STFT- short term fuel trim, or LTFT- long term fuel trim.

The MAS is the primary sensor used in the calculation of the initial injection pulse width. When the sensor becomes open or shorted, the control module sets the code along with the operating conditions in which the fault occured. This would typically cause an intermintent hesitation upon acceleration.

Since this is not what is happening we look at what other sensors communicate with the ECM in conjunction with the MAS , which is the O2, the P0130 that is pending is... O2 sensor circuit problem bank 1 sensor 1, which makes perfect sense. Since the O2 manages fuel trim, and there is a code for fuel trim, what I think... is that the O2 had/has an intermintent short/open that effected STFT,LTFT that in turn set the code.

Diagnosis: Scope the O2 for function, check connections

Have fun

inspector1,

Thank you for the insight. I do have some types of delay when accelerating from cruising speed on the freeway. But I can't tell if this was due to transmission slipping or hesitation upon acceleration. When cruising on freeway, if I step on my gas peddle all the way down to the floor, the car will not speed up right away. I had to accelerate slowly to increase the speed of the car from the freeway cruising speed. I thought this may be due to the way the car was driven (always accelerating slowly) and the computer learned the pattern of the driving style that the abrupt acceleration was not recognized by the computer.

Anyway, I cleared the codes on the car yesterday and after two driving cycles the check engine light came back. P0170 again. Check the vacuum hose, did not see any loose connections.

" I do have some types of delay when accelerating from cruising speed on the freeway. But I can't tell if this was due to transmission slipping or hesitation upon acceleration. When cruising on freeway, if I step on my gas peddle all the way down to the floor, the car will not speed up right away. I had to accelerate slowly to increase the speed of the car from the freeway cruising speed. I thought this may be due to the way the car was driven (always accelerating slowly) and the computer learned the pattern of the driving style that the abrupt acceleration was not recognized by the computer."

MINE does exactly the same. i however do not get a check engine light? i have posed this question somewhere else as well.
will i have codes stored although i do not get a check engine light and if i have disconnected the battery. the shops tell me "no light-no code"

:(

spikes,

get a hold of an obd II scanner. the one i have will show pending codes.....meaning the computer sensed something wrong but did not trigger the check engine light yet. I don't think my sympton is the same as yours since I seem to remember reading your other posts that your car shakes when you accelerate (mine doesn't shake at all).

also, if you disconnect the battery, you will lose what ever codes that are stored in the memory.

hope it helps

thank you.

mine has a vibration and has to do with tranny or flex disc. i am putting back the old flex and want to "reverse" the process to see if it vibrated before.

i will try autozone tommorow and get some codes. my car's symptons are exactly what you describe.

thanks for your input
spikes:D