Where is my upstream lambda sensor?

[Dek]

(Newbie)...Morning all
First time on forum here's hoping some one may be of assistance!
I have recently purchased a Mercedes C class 320 cdi 2008 with quite a few issues which I'm slowly working my way through them.My main gripe at the moment is heavy black smoke out off exhaust on heavy acceleration & engine light on..I've plugged in my basic obd reader which came up with code p0132 02 sensor circuit high voltage Bank 1sensor..Replaced 'post Cat sensor' but no improvement.
Friend then plugged his super dooper obd reader in witch came up with DTC 115100 Lambda sensor upstream (pre cat) signal value too high intermittent.
My problem is I can't find it! Lol.....Bit confused as some are saying there's only one (post cat)...Euro part list one as upstream so do Mercedes....Any information would be greatly appreciated!

 

[Petrol Pete]

Hello and welcome . I don't know where it is on your car but it is usually pretty obvious when you are under the car , it's the one sticking out of the tapping in the exhaust flow directly after the cat.

My tip is when you do find them both check all wiring and plug connections if OK remove and clean the sensors then drive the car with the code reader set to live tracking of 3 things , both sensors and the temperature of the cat. If the sensors are returning some kind of voltage and the heating circuit is not broken you will see it on the screen indicating that they are actually doing their job.

You will see on the live trace if anything is coming back from the sensors and if the voltages are too close and not within limits it would indicate that the catalytic converter is not working properly.

And as you probably know 5 seconds of visible black smoke is an MOT failure as a 'major' issue. Let us know how you get on

 

[W1ghty]

There is only one lambda sensor on the non dpf om642 engine , it’s next to the gearbox sump , easily visible with the underside plastic shields removed .
When my lambda packed up it didn’t trigger black smoke buddy

 

[Petrol Pete]

That's what I am thinking W1ghty (didn't know it had just one) but I suspect something else is wrong and the sensors is actually working. Like I suggested not particularly difficult to check operation with a half decent scan tool . OP will be back

 

[BlackC55]

Check for boost leaks. The Lambda sensor wont cause black smoke.

 

[Dek]

Thanks for reply Chaps!....so to confirm there's only one lambda sensor!
I've done live scans on my basic obd reader & this is what's happening on idle!..(just trying to down load them )
Apologies for picture quality...Can anybody draw a conclusion from these?

 

[Petrol Pete]

O2 sensor is reading 0.922 V so it's working. Not sure what the V should be on yours but recently on my Petrol Toyota Yaris S1B1 was 0.780V and S2B2 (after the cat) was 0.700V with the cat at 622'C intake and 620'C outlet if that helps.

Why is your scan tool on non metric settings ? something you prefer ? just curious.

 

[Dek]

Thanks for reply Petrol Pete...I think the volt reading should be max .9v I've just been out & done a live reading,it varies anything from
0-1.3v fluctuating!...Would an hours diagnostic at Mercedes tell anything more procise in you opinion?

With ref to my scanner being set on 'non metric',only used it a couple of times & havent changed the values over!..

 

[Jigglyjohnson]

Have you checked the air filters as the om642 suffer with the air filters blocking up rather quickly. Also checked the egr system make sure it is working correctly. Does the car perform correctly no lop ?

 

[Dek]

Hi Jiggly..I've just done a full service on it which included 2 x air filters amongst the other std service items!...Had the egr valve out & gave that a clean & was moving freely....The car performs well achieving 37 mpg on a decent run & responsive it's just the fact it chucks this black smoke out on hard acceleration!

 

[Jigglyjohnson]

Does it smoke all the time ?? Or only when hard acceleration ?

 

[Dek]

Only on hard acceleration...you can rev it on stand still & its clean!