MAF light persisting

Hi, I have E200 K 2001 sedan.EMS light came on at 104000 Kms. Changed MAF meter and sensor as well as check valve.Lihgt comes back in 2 days.Reset agian by garage,comes again in 2 days.It is persistently on now.Have spent so much money to no vail. Please someone help.
bonedoc

Hi,
The first thing you need to do is to get the Diagnostic Codes read.
In the USA this can be done for free at many garages.
Once you have the coide come back and we will advise what the code means and what needs to be done.
Stuart.

Concur. Obtaining the error codes is everything and of course clearing the error codes after replacing/repairing the actual and real problem item or device.  Let us know the what the diagnostic error codes readings are and what your garage that obtained the error codes NOW says needs to be done. thanks 

There are several reasons MAF Sensor can set a code.  Let me take a guess...Code *P0170 or *P0173 Self-Adaptation out-of-range.  Usually, this means that either the engine is either too lean or too rich.  These values can ONLY be check using an SDS (Star Diagnosis), and not any scanner (e.g. Snap-On Tool, or Any Scanner).  That's the advantage of having an SDS...like me!!! :>)  Anyhow, I strongly doubt that a garage or a gas station in either U.S. or U.K. would have such a Diagnostic Tool.  Because first, you have to have worked at a dealership for quite some time to be able to navigate through this system.  Okay, going back to your question...
 
Here are several possibilities: First is Mass Air Flow Sensor, which after replacement should be reset through Control Unit Adaptations (Throttle Valve Angle, Zeroing out the previous actual values, etc.).  Second, a dirty Air Filter can cause it as well.  Third, low fuel pressure causing incorrect air/fuel mixture ratio readings from Oxygen Sensors.  Fourth, cracked Intake Hose causing vacuum leak.  These are some possibilities that you might want to get checked.  Wish I was in Dublin...I'd like to visit there one of these days.
 
take care,
-mar-

Hi,
I hate to disagree with you BUT OBDII DTC's (On Board Diagnostic Codes) can be read by ANY OBDII compliant scan tool. Its an International Standard.

Navigate through the system. You plug into the 16 pin OBDII port, turn on the ignition, and any codes (pending or stored) are displayed. It so simple that this is why SOME garages. especially in the USA. will scan the OBD and tell you what codes are set in order to get the repair job. It literally takes 2 minutes.

P0170/P0173 is the classic SIGNATURE of a faulty MAF. Codes do not tell you what needs to be done to rectify a problem. The code tells you what ECU parameter is wrong.

You refer to Self Adaptation...this is an MB term...more commonly known as Fuel Trim. The STFT Short Term Fuel Trim advises how much away from IDEAL (in % terms) the real time fuel mixture is.
The LTFT Long Term Fuel trim is the "self adaptaton" value which is basically a start up offeset or baseline correction. The value of STFT and LTFT can be determined with any OBD compliant scanner with REAL TIME DATA CAPABILITY.

I use a DynoScan (from Auterra.com). Cost me 150 USD and runs on my Palm PDA. very handy. No power leads etc and has been rock solid for the last 4 to 5 years. Many other manufacturers make such equipment for similar price. Most run on a PC laptop.

The P0170/3 signature usually points to a dirty or bad MAF and the sensor needs to ber cleaned or replaced. Its the MAF sensor that causes the fuel trim to be wrong rather than the other way around.

Yes dirty air filter, bad O2 sensors etc can also cause similar incorrect "Adaptation" values but these do not give the P0170/3 code signature.

Although I have no MB specific training Bosch Electronic Injection system (as used by MB) is used by many manufacturers...or at least extremely similar concept.

Hope this helps.

As I stated previously. GET THE CODES READ and come back.

I suspect you will find a P03XX code showing (Misfire) however there are many other possibilities. If you have a P03XX code the first thing to do is to check the plugs and leads.
If you have a P0301 (Cyl 1 misfire) swap the plug and lead with lets say No 4. Does the problem move? i.e. the code becomes P0304. If so you know its the lead or plug causing the problem. If not then need to do similar with injector. If many cylinder misfire on just one bank (assume V6/8) then the O2 values and possible codes are important.................

Incidentally plugs should be chhanged circa 75/100k dependent upon engine type etc.

I have three OBD II Scanners...one is Snap-On 7.4 ($6,500)...second is OTC Scanner ($1,500), another Generic Scanner ($100), which is the same as what Auto Zone to use to check codes, and I use this $100 Scanner for my CODE READINESS.  That's the reason why your Check Engine Light keeps coming back because every time someone resets the codes, it erases ALL the "Code Readiness" Monitor, and you have to drive it for several miles and go through a Drive Cycle. Hmmmmm...Using the SDS (Star Diagnosis) gives so much access (e.g. programming Instrument Cluster (e.g. mileage), Programming ME-SFI, ETC, PSE, SAM's, Telematics,....etc...name it...I can do it using SDS.  Something Snap-On or other Generic Scanners can't do.  However, there's Auto-Logic, which is usually mostly European cars, but you have VERY limited access.  It was really design for (BM-Trouble-U's) another short name for BMW.  TRUST ME ON THIS...SDS is the BOMB!!!  Dirty Airfilter can give *P0173 and *P0170 codes.  If the MAF Sensor is not receiving the correct volume of air passing through the MAF sensor...this will through off you readings.  Trust me, I see it when Techs replace Air Filters all the time and not clean the Airfilter housing, the next day Check Engine Light comes back with MAF Sensor coding.  These are advice I give you guys...take it for what its worth.  Also, there is a TSB (Technical Service Bulletin) for quite some time now....probably when they started building the 112 and 113 Engines, which was 1998. 
 
take care,
-mar-

Hi mar,

I'm always willing to learn and sense that you may have valuable input especially with your MB credentials. However I cannot agree with your post.

SDS Star is undoubtedly the very best diagnostic tool on an MB. After all it is the MB approved equipment. However thanks to OBDII (circa 1998) engine management codes were standarised and can be read by any OBDII compliant scanner.

What many OBDII scanners CANNOT DO is to access the body and chassis ECU codes, live data and activation routines, and in particular the Instrument pack for mileage "adjustment" etc. For this you need SDS / Autotech etc which is mega EXPENSIVE equipment. I would love to have SDS kit!

However we were talking ENGINE/TRANS codes which are OBDII compliant (by law). You do not need SDS to read these. Try http://www.auterraweb.com/dynokitsnohotsync.html

I also note your statement...
If the MAF Sensor is not receiving the correct volume of air passing through the MAF sensor...this will through off you readings.

The MAF measures air flow (Mass Air Flow) so if it is working correctly it will measure the flow of air. However IF the air flow is SEVERELY restricted the flow of air over the sensor is impacted turbulence / non laminar flow) and this may impact readings.

Trust me, I see it when Techs replace Air Filters all the time and not clean the Airfilter housing, the next day Check Engine Light comes back with MAF Sensor coding.

I find it difficult to understand how an air cleaner HOUSING can get that dirty. The filter YES.
My 130k M112 air cleaner is "as new" both outside and inside.

Returning to BONEDOCS problem. He replaced the MAF without determining what codes (if any) had been set. MAFs do give problems at circa 75k + miles but many other things can cause the CEL to illuminate. It is always good diagnostic practice to be able to turn the problem ON / OFF. Only then can you be sure that you have identified the real issue.

In addition it is also important to ensure that normal routine maintenance / service is up to date prior to embarking on changing parts without adequate diagnosis / analysis.

Lets wait and see what codes are pending / stored.

Stuart

Let's wait and see which codes he has, and we'll perform process of elimination...
 
take care,
-mar-

I agree that you can check codes with any scanner.  My $100 scanner can do it, but I'm very limited as far as pinpointing what the problem is.
 
take care,
-mar-

Hi All,
        Thanx a lot for the inerest in the topic.Just to set the record straight....Engine light came on at 104000 kms(E200 Komp 2001 model).Went to local garage....checked the code...it was....P2036..Intake air device,wrong operation,air entry too small....that was exactly what computer read....he changed MAF and reset.....light back on in 2 days...reset again...still bright as sunshine....please help.look farward to solution.
 
Thanx.
bonedoc
dublin.

Hi Stewart,
Thanx a lot for the inerest in the topic.Just to set the record straight....Engine light came on at 104000 kms(E200 Komp 2001 model).Went to local garage....checked the code...it was....P2036..Intake air device,wrong operation,air entry too small....that was exactly what computer read....he changed MAF and reset.....light back on in 2 days...reset again...still bright as sunshine....please help.look farward to solution.

Thanx.
bonedoc
dublin.

104k. = 60k miles. Nothing.

P2036. Not sure that the code definition is correct. My scanner gives a Generic OBD definition = Exhaust gas temp high bank2 sensor 2. However since yours is a 4 cyl this doesn't sound correct either. P2xxx codeds are not very common.

Certainly the code that you have up is not typical of a MAF problem. You have confirmed this since a change of MAF has not resolved the problem.

Are you sure that the code is 2036. It isn't one of the usual codes. Not very familiar with Kompressor so could be a Kompressor code but don't have any experience.

Any symptoms other than the CEL?

What were the conditions when the light came back on. Hard accel, cold engine etc etc.

Stuart.

Again, it's either a clogged air filter or vacuum leak. If I'm not mistaken, that's the same code as *P0173 and *P0174.  If MAF sensor is new...then check the other two that I've recommended. 

IMHO

P0173 / P0174 point to different faults.
Both are lean fuel mix related but due to different causes. P0173 is electronic adaptation (Long Term Fuel Trim) is out of range (= MAF sensor) whilst P0174 is due to "other" causes like the air filter.

So what is the official MB definition for P2036 please?
Do you actually have a list of MB specific codes vs the standard OBDII codes which are readily accessible on the internet?

Sounds like masterbenz is correct if P2036 = P0174 (Intake restriction) but why do MB use two totally different codes for the same thing?
Any ideas please masterbenz? Maybe its because the Kompressor is not normal equipment on all engines and it therefore has a set of codes similar to, but different from, the standard OBD codes. There is always something new to learn and I know very little re MB Kompressor having never owned or worked on one.

Stuart

Hi Thanx,
            Accelration seems to be slow at low speed...(i mean 0-60 is slow) once it gets going acceleration seems good.First time when light came on it was cold and started after a cold night soon after starting. After resetting almost always comes on about a mile after start being parked for about 5-6 hours.
Should I run the engine while parked without air filter to check if that is the problem of slow intake? would the light go off on its own if problem is fixed or it has to be rest? sorry if i sound too silly
Thanx again
bonedoc
dublin

Silly. Of course not.

I'm at a disadvantage because I'm not as familiar as mar re the P2036 code nor with Kompressor.

However I guess a key issue is how soon after the inlet system change the fault occurred.

You can run the system with filter removed for a temporary period but of course you need to understand the risk of some debris being sucked directly into the engine. The odd fly may not be a problem but a bit of grit would be!

Something tells me this may be a kompressor related problem BUT I only guessing...not good practice!

The garage you whent to was an MB dealer? Sure the MAF that was fitted was a genuine MB or at least OE Bosch. Spurious aftermarker sensors can give "strange" results.

Stuart

The CEL will usually reset itself after a number of cycles (dependent upon initiating fault) with the fault removed.

They change some coding numbers at times, such as this!!!  This should help, and READ THE NOTE AT THE VERY BOTTOM!!!
 
Air Mass Sensor Replacement Due to Codes P2004, P0170 and P0173
If you receive customer reports in the above model vehicles of the check engine light coming on and codes P2004, P0170 and P0173 are stored, prior to replacing the air mass sensor refer to the following procedure.
























Error Code P2004 splits into four subcodes (Figure 1) to provide more detailed information regarding the source of the fault.
























Test voltage supply 5V (Figure 2) and 12V (Figure 3) of component B215 (hot film MAF sensor).
If test is OK, proceed to step 2. If test failed, perform the following:




-
Check 12V voltage supply from ME control unit.


-
Check connection point for ground of ME control unit.


-
Check wiring harness and Z-connection (Z7136) from the air mass sensor.


-
Check for other error codes from components (pressure sensor, oil quality sensor, etc.) which receives 5V voltage supply from the ME control unit on the same line.

Error Code P2016-[1], P2017-[1], P2018-[1] (P0170) and P2085-[1], P2086-[1], P2087-[1] (P0173)
























Step 2 - Test signal voltage of component B215 (hot film MAF sensor) by means of actual value (Figure 4).
Check for the voltage value of the air mass sensor with the ignition ON (engine not running).
Voltage range must be between [0.980 - 1.030V].
If the air mass sensor voltage is out of range [0.980 - 1.030V], replace the air mass sensor.
If the air mass sensor voltage value is in the specified range [0.980 - 1.030V], check for any air leaks in the air intake system.
























In particular on models 170, 203, 209, 211, 215, 220 and 230, check for proper installation of the air mass sensor to intake manifold (Figure 5 and 6 are examples of improper installation)
























If necessary, correct the installation of the air mass sensor to the intake manifold (Figure 7 and 8). Do not replace the air mass sensor.
Note : Before replacing the air mass sensor, check for sand and dirt particles in the clean side (between air filter and engine) of the air intake system and clean if necessary. Check complete air intake system with air cleaner and repair as necessary.

Return air mass sensor must be accompanied by air mass sensor voltage screen printout (Figure 4) and OBD-Code freeze frame data. Returned air mass sensor with voltage range between [0.980 - 1.030 V] or without this print outs will be debited back to the dealer as of repair date July 24, 2003.

take care,
-mar-

But P2036 is NOT P2004.

Definitiion of P2004
MAF sensor wire harness or connector problem (voltage low, high, fluctuating, implausible). Fits in perfectly with the document you have posted.

I don't actually have an MB definition for P2036. The OBDII Generic definition is Exhaust gas temp Sensor Circuit Low.

Mar - Do you actually have an MB definition for P2036?

Thanks

Stuart.

Hmmmmm...I have to check on that...give me sometime to research it, and I'll find out...hopefully.
 
take care,
-mar-