HELP on Fault Codes please…

[JameSlk]

Hi,

Firstly I hope this thread is in the right section!

Some of you may have seen a thread I made recently (http://www.mbclub.co.uk/forums/electronics/207585-cheap-diagnostic-scan-tools.html#post2278984) about diagnostic scanners, which one to get, as unfortunately my CEL came on recently.

Anyway, tonight I saw a friend who has a Snap On one, and these are the 3 codes that came up;

P0101 Mass or Volume Air Flow Sensor “A” Circuit Range/Performance
P0172 System Too Rich Bank 1
P0136 O2 Sensor Circuit Bank 1 Sensor 2
P0141 O2 Sensor Heater Circuit Bank 1 Sensor 2

My friend looked at the MAF flow rate on tick over (engine was warm) and it was at 2.58 g/s. Is this normal?

The O2S Voltage Bank 1 Sensor 1 was at 1.401V. Again, is this normal?

Please see the attached 3 pictures I took of his screen, it may have some more info that could help.


What are people thoughts on the fault codes I have/had? The car seems to be driving spot on by the way! Do you think I need a new MAF sensor? Can I clean my existing one with contact cleaner?

My first thoughts are it may be worth trying a new MAF or cleaning it, as I assume the 3 fault codes are linked, and maybe a dodgy MAF that is over reading is causing the car to over fuel and thus the bank 1 sensor 2 lambda probe is being screwed up. I don’t know, I am guessing! What are your thoughts?

Also which lambda probe is the bank 1 sensor 2? On my other car it has 2 lambdas, bank 1 (pre cat) and bank 2 (post cat). Does my 2008 SLK200 have 2 lambdas pre cat or something?

Finally, thought I’d mention, I noticed in the service history of the car which I bought only 15 days ago, that back in Sept 2014 it had a new “O2 down stream sensor”. Wonder if that’s the same lambda sensor in question?!

Thanks for reading, hopefully you can help.

James

 

[JameSlk]

EDIT: Just realised in my picture there is in fact a 5th code; its the first one which is highlighted in black, why it's black I don't know, maybe it's an old stored code, especially as it contradicts the system too rich code! Anyway...

"P0171 System Too Lean 1"

 

[JameSlk]

Anyone? lol

 

[sicelo]

Maybe start by clearing all codes to see which ones come back. this will help you know what is current and what is not.

Yes, replacement MAF may be a good idea. If you are able to get a MAF just for testing first, that would be great. If you opt to clean it, be extra careful as they are sensitive buggers. Your long term fuel trims do show a lot of fuel going into the engine, and of course, the MAF is the leading cause for such issues. However, also check for the simple things: vacuum leaks ... You've got nothing to lose here.

but going by that readout, your MAF is not operating optimally. I guess there have not been many responses because the issue is a little too obvious

anyway, I don't really know your car, nor do I understand engines too well. This is based on the little research I've been doing lately to cure my W202 problem. I have P0170, and now know for sure it's a bad MAF.

As for the O2 sensor that was replaced .. it is possible that it was not put in correctly? or cheap aftermarket part?

not knowing the snap-on, but I think the first code is black because that's where the "cursor" is all of the other pictures have black parameters at one point or another

 

[JameSlk]

Hey, thanks for your reply!

Yeah that’s my plan, the codes have been cleared and see which ones come back and take it from there, I’m assuming I will be needing a new MAF soon! £187 for a Siemens VDO one, which I assume is OEM, from Euro Car Parts.

I guess I could try CRC MAF cleaning spray first, but probably a waste of time/money/effort.

I spent a good hour today looking for any splits in pipes/vacuum leaks etc but no joy. That said, I found 2 small areas where there is a slight presence of oil, so there may a split breather pipe somewhere, but I couldn't see any. I think I read the other day that there are breather pipes which often split under the inlet manifold, but that was on another Mercedes, but I assume mine will also have some pipes there too. I couldn’t see under the inlet manifold though unfortunately!

I have attached some pictures of the 2 areas I saw small amounts of oil present. One was on a plug behind the throttle body and the other looked like maybe some oil underneath behind the ECU, well I assume it’s the ECU?!

Can anyone please confirm if there are breather/vacuum pipes under the inlet manifold, and whether they often split? I assume there must be, I cant see how else the oil has got onto the plug behind the TB.

 

[JameSlk]

Bump for the post above!

 

[JameSlk]

Anyone?!

Hey, thanks for your reply!

Yeah that’s my plan, the codes have been cleared and see which ones come back and take it from there, I’m assuming I will be needing a new MAF soon! £187 for a Siemens VDO one, which I assume is OEM, from Euro Car Parts.

I guess I could try CRC MAF cleaning spray first, but probably a waste of time/money/effort.

I spent a good hour today looking for any splits in pipes/vacuum leaks etc but no joy. That said, I found 2 small areas where there is a slight presence of oil, so there may a split breather pipe somewhere, but I couldn't see any. I think I read the other day that there are breather pipes which often split under the inlet manifold, but that was on another Mercedes, but I assume mine will also have some pipes there too. I couldn’t see under the inlet manifold though unfortunately!

I have attached some pictures of the 2 areas I saw small amounts of oil present. One was on a plug behind the throttle body and the other looked like maybe some oil underneath behind the ECU, well I assume it’s the ECU?!

Can anyone please confirm if there are breather/vacuum pipes under the inlet manifold, and whether they often split? I assume there must be, I cant see how else the oil has got onto the plug behind the TB.

Anyone?!

 

[sicelo]

Give VIN .. can look for you on EPC if it's not too hard to see (I'm no EPC expert, and as you can see from my profile, I have an older car than yours). Why don't you just look under your own car? You would have found out the answer long ago.

 

[JameSlk]

Have you got a link to a decent EPC? That would be great! I found a couple online a while ago but they were foreign and hard to use and I had no joy unfortunately. At that point I was looking for the MAF diagram to aid changing it! A diagram of the breather pipes would be awesome!

ps. Thanks for the reply! lol

 

[sicelo]

interesting that you never respond to any question you're asked ... i don't think that's nice

anyway, Mercedes-Benz for 17vin.com

Good luck

 

[JameSlk]

Sorry are you being sarcastic? I have just re read your post #8 and see that you asked for my VIN ("Give VIN") is that correct? I thought you were being sarcastic then, as in saying to give in! lol

I can PM you my VIN if you want?

EDIT, I have just looked at your website link with my VIN details, and I cannot find the diagrams for MAF or breather pipes! Will PM you my VIN in the hope you can do better than me please!

 

[sicelo]

MAF is number 10 in Mercedes-Benz Car Maj. assy M?Engine 271954 M271 KE18 ML FUEL INJECTION AIR-MASS SENSOR,THROTTLE VALVE ACTUATOR; USED WITH MOTRONIC for 17vin.com

Hoses are in Mercedes-Benz Car Maj. assy M?Engine 271954 M271 KE18 ML ENGINE HOUSING CYLINDER CRANKCASE for 17vin.com

 

[JameSlk]

Thank you very much!