Had my check enging light come on

[kjf1234]

Pulled the code P0170 - anyone have any info on that

Also wanted to pick up a code reader need one to just do the job any suggestions.

Thanks you

[jlomon]

From what I've read on MercedesShop.com, this code is related to fuel mixture adaption. That means the controller has tried to repair a mixture problem and couldn't within the software parameters it was built with (I read this from Steve Brotherton, one of the techs who helps out on that site).

The likely culprit is your Air Mass Meter (also called Mass Airflow Sensor by some) which is a common W202 fault. But it is not 100% sure, so have your car looked at by a competent tech.

[JOESID]

I had P0170 and I was skeptical that it was the Mass Air Flow so I had the indie Mercedes shop do their tests, and they told me it was at its "limit" and would need to be replaced very shortly. I bought a new one, installed it, and the light went off within a few days.

[SLAMMED_C]

yep.. po170 is indeed for self adaptation being at its limit.
in almost all cases the proplem is the MAS.. but it can also be a vacuum leak, intake manifold leak, leaking injector seals.. pretty much any air leak where air can get into the engine, and that isnt being metered (by the MAS).

[renerodz]

I had that code before, on my ML320 though. I cleaned the MAS using 91% alcohol and put back. I also used some silicon oil on the gasket of one of the sides and on the other clamped side.

This was 24K miles ago, although I think my real problem was a leak on the rubber gasket on one of the sides. I had no pending codes or CEL after that.

This should be consistent with slammed_c approach. Maybe the cleaning of the MAS was not the real cure.

Hope this help.

Thanks,

Rene

[renerodz]

Sorry,

This was supposed to be a reply to thread: "Had my check enging light come on"

Sorry again for messing it up.

Rene

[fltrplntman]

I had my CEL come on twice with the P0170 code. I ended up cleaning my MAS with fast drying , no residue, electrical contact cleaner. 9 times out of 10, you wires are dirty on your MAS. Just clean them.
Take the MAS off the car, spray the wires (off to the sideof the housing) with the contact cleaner and let it air dry for about 10 minutes to make sure there is no chemical or residue. Do not take the MAS out of the side of the housing. You'll risk braking the wires. Then you are screwed royally. after it dries, re install it. Piece of cake. If you can change your own air filter, you can do this. Then disconnect the battery to reset the Check engine light.

The code P0170 pertains to the improper fuel trim. P0171 is your MAS going bad. Don't let the shop kid you into buying a new one with the wrong code.

[kjf1234]

I am new with german cars where is the MAS located and how do i take it off

thanks you for your help.

I should let you know i took it to the dealer twice so far they cleared the code twice told me that for both times there was a vacume leak on the manifold and that its fine . THE LIGHT CAME ON AGAIN today just got the car back from the shop yesterday.

THANKS PEOPLE
PEACE

COULD IT BE A BAD GAS CAP BY ANY CHANCE

[fltrplntman]

The Mass airflow sensor is located in the air tube going from the air cleaner to the throttle body. Its black and is about the size of a beer can with a small wire harness coming from it.
Just unplug the wires,

undo the hose clamp,

and unlatch the sensor body from the air cleaner tube.

Off to the side are the wires in a plastic housing. The wires are hard to see because they are about 1/2 inch long and very thin. Look closely... you'll see them.

I recommend CRC QD Electronic Cleaner. Dries fast, no residue.
Spray the wires from both ends of the tube liberally. (i used about 1/4 can.)

Let it air dry for about 10 minutes to be safe.

In this amount of time, Disconnect the Negative cable on your battery.

Re install the MAS and reconnect the battery.
Let me know if your light stays out this time. :-)

[Rocky]

I had a P0170 fuel trim CEL on my old C36. I cleared the code by totalling the car :P

Seriously, I'm not sure it's the mAS because I had it changed. I had a feeling ti might be the throttle actuator.

[fltrplntman]

Or did they? Hmmm. :-)
There are several thing that cause the code. Air leaks, maybe a loose fuel filler cap (haven't got confimation on this one yet) plugged or dirty airfilter? All I know is that this method should be used BEFORE replacing the MAS on this code. (P0170) P0171 is the code that points almost directly to the Mass Airflow Sensor.
$6 verses $500... Worth a try, don't you think.


Seriously, I'm not sure it's the mAS because I had it changed. I had a feeling ti might be the throttle actuator. [/B][/QUOTE]

[kjf1234]

Well i stopped at the MB dealership bought a new gas cap and put it in drove around for a bit and the light went off. it was off all of one day came on and then went off again now it on again . I am going to change the air filter and see what happens .

THANKS A LOT GUYS . If that fails goign to clean the MAF and see what happens . The car drives perfectly though .

[kjf1234]

my low gas indicator was blinking today . what does that mean?

i shut the car off and on again and it stopped blinking any ideas is it all related?

[jnolte]

Originally posted by kjf1234
my low gas indicator was blinking today . what does that mean?

i shut the car off and on again and it stopped blinking any ideas is it all related?

it means you got a leak in your gas system somewhere, tighten the gas cap

[fltrplntman]

Originally posted by kjf1234
my low gas indicator was blinking today . what does that mean?

i shut the car off and on again and it stopped blinking any ideas is it all related?

Ummm... Put some gas in it?? LOL
I have seen other post about the sending unit in the tanl going bad. Do a search on this site and MBworld.org
Something ought to show up.

[RehGeeBenzo]

cant u get code reader from like ne place like autozone for free?????


i would like to know because my engine light comes on also somtimes

[Denlasoul]

Originally posted by RehGeeBenzo
cant u get code reader from like ne place like autozone for free?????


i would like to know because my engine light comes on also somtimes
Yes.

[fltrplntman]

Advance Auto Parts scan ECU's also. They print out your codes for you. Let me know what they print out for you.


Originally posted by Denlasoul
Yes.