phyberlink

Hi all, I need help please. I have a C 280 1996 in Virginia, I got a Check Engine light, My friend who works with me, has an OBD II Actron AutoScanner Model CP9175, and it reads "P0170 fault code for fuel trim malfunction Bank 1 of 1" Now if I happen to have a leak, then what should I replace, is it a mini hose or a relay or a fuse? to replace, I have no clue what to do. Meantime my friend erased the light, but after 80 miles the "Check Engine" light came back on, what part should I buy and replace myself? Alco the car runs fine, Thanks in advance I really do not know very well how to use forum, where is the "How To" navigate to make the most of this Forum ? Thanls

PaulX608

That code usually points to the Mass Airflow Sensor. Pull it, clean it, reinstall it. If problem persists, replace it.

phyberlink

Thanks Paul, Is there a diagram ? of the MAF location? I will try to find it on the Internet or perhaps on Youtube, but if you know of a good source as to pin point the location under the hood I would appriciate it. Thanks

PaulX608

It will be along the intake tract between the filter and the throttle body. It'll be a tube with a sensor in the side of it.

Part 80 in this diagram:

phyberlink

Thanks for the diagram, this helps, can I purchase this ? http://www.ahwooga.com/detail.asp?id=61028

PaulX608

Looks like the right part to me.

phyberlink

I purchased a can of BG Mass Air Flow Sensor Cleaner $10 Bucks, I removed the Sensor ONLY, but it was very clean, I sprayed it anyway, put it under the sun to dry, I then removed the MAF housing and I sprayed it too! After confirming that all is dry, I put everything back together, I started the car, everything is fine, but the "Check Engine" light is still "ON". I did not erase it, I am now driving to reach over 100 miles and see if it will go away. My office is just 4 miles from home, so it will take a while to reach 100 miles. I believe that the Fuel Filter has not been changed for the last 6 years. I found the Air Filter Very dirty, I went to two auto supply stores and no one have it, and so I ordered a MANN from autohausaz.com, will be in shortly, I cleaned the air filter as well as the housing, vacumed it, was full of bugs, sand, leaves etc. The car runs great and smooth, in fact it starts better than before. By big question to you the Group is: What should my NEXT course of actions be, without making financial mistakes? I really do not think it is the MAF, only because it was very clean already, and I also handled it with great care, and I only sprayed the bottom.

phyberlink

I was told by two Mercedes Service shops that I need to check for vacuum leaks first, before I replace my MAF. How does anyone check for vaccum leaks? I am getting a code P0170 still. How can I find a vaccum leak?, how can I fix it, where to look!

ohlord

or you would have other issues besides fuel trim value.
also that maf you looked at is a chinese clone piece of crap in other words.
Do not use it.
1996 C280 M104 engine uses either the round or square elongated harness plug shape maf you will need to look at the one on the car and then order the real oem bosch part from a reputable supplier like www.autohausaz.com
If you want to assuage yourself about a possile leak in the intake system that would throw the ft code it won't be a vacuum leak it would be an actual air leak into the intake aft of the maf.
Vacuum leak and it would not be running as nicely as you say it is.
look for cracked or broken hoses. Maf not fitted properly etc.
if you won't sleep without first checking for vacuum leaks PM me and I'll tell you how.
And then replace the MAF
If you cleaned it and have driven it and it was sorted out by the cleaning the code would be gone by now. It is not,so the maf is shot. The fault in a maf is not that they get dirty in a few cases cleaning helps for a short time. The issue is the thermistor in the element burns up and falls out of range.
For under 200 bucks and 10 minutes of your time you will be ahead of the game since a shop will be glad to charge you at the minimum 2-3 times that amount. Seen it go as high as $880 ripoff
It is time for a new fuel filter from autohausaz also since air filters,mafs and fuel filters go hand in hand.

phyberlink

Here is a picture of my MAF, My car is a 1996 but Production Date is 10 1995, October. It is confusing buying it from AutoHauseAZ, cause there are 3 to choose for the 1996 C 280. Why can't I select the cheaper one? go figure! I will work on my car this Sat and see if all the hoses are tight and then turn on the engine and put my hand around and see if it is blowing air, or sucking air somewhere. I want to get a genuine bosch, I will also buy a Fuel Filter, but I never replaced one before! I need help on that one. Is there a diagram of the location of the Fuel Filter? can an amateur like me do it? I have a garage and plenty of tools from Sears Craftsman. Thanks in advance for additional advise.

phyberlink

Check Engine light just came back ON, this is after I cleaned the MOT Valve.

ohlord

the purge valve,not the mass air sensor.
The purge valve has nothing to do with fuel trim.
The maf you need is the one ending in 7500
like this
you won't find an air leak by hand,

phyberlink

Yes, I did clean the MOT valve, I removed the two mini black rubber tubes, the "IN" & "OUT" tubes, I then sprayed these tubes with BG MAF Cleaner spray, I then put the red spray can tube in the actual MOT Valve, and sprayed the inlet and the outlet, I put everything back together again, went for a ride for 10 miles. No change. Please help. Thanks

phyberlink

Today I found out my Vacuum leak, please review the pictures. On the MOT A0004702293 Regeneration Valve The is a half circl black rubber tubing that is cracked and in the middle of this curved tube yet there is another mini tubing that branches out. I need the part number please, in so to order it and replace it and be done with this problem, I have suffered enough already. Please help. Thanks in advance.

phyberlink

Here is more photos