S320 (new to me) Loss of power - engine management lights - dpf sensor

[MB8701]

Hi Guys,

Only had my precious s320 a week however I encountered a problem on Friday with the yellow engine light coming on so through recommendations from this site I went to stephen at knightswood service Centre Limited in Glasgow.

Anyway they plugged it into a laptop ( I assume STAR) and it popped up with just one fault code for the DPF Sensor.

DPF sendor replaced after a nice 200 quid later (which I thought was steep) but anyway it looks like the problem has came back just 12 hours later.

Just wanted to get some insight into if it can be something else.
My biggest issue is garages just starting to charge and change parts for the sake of it just because a laptop says and don't want to end up spend hundreds or thousands for things that don't need done.

It could be a complete freak of a chance that the second DPF sensor was faulty but thinking what else it could be.

Any help would be great.

 

[Borys]

I hope you didn't open a pandoras box
On mine needed to replace manifolds (swirl problem), swirl flap actuator,egr valve was seized too.... And then a turbo
Faulty actuator will give you a limp mode,loss of power but star should detect the fault
Problem on these engines is a leaking seal on induction pipe to a turbrange colour top of the engine,running between heads.It seats above actuator once leaking...all goes wrong
I guess elimination process now

 

[MB8701]

I really hope that is not the case. I would be rather upset.
Would all those issues not show up on star. The car drove flawless before that and when the dpf sensor was changed it was perfect again for a day so I don't think it would be egr valves or swirl flaps or anything major.

What are the signs of the seal being faulty.

 

[MB8701]

Anyone else had any experience of this -
When it was connected to star - only one fault came up and that was the DPF Sensor and nothing else.

As I mentioned the car drove perfect before that and after the DPF sensor change but the fix only lasted a day and then went back to limp mode again.

I am thinking if it may just need a forced regen of the DPF

 

[mersum1es]

Regen is worth to try, what was ash content reading?

Could also be blocked cat/exhaust...

 

[Borys]

Does it goes to limp mode still?

 

[MB8701]

Does it goes to limp mode still?

it went into limp mode 12 hours after the dpf sensor change.
It was flawless for 12 hours then it went into limp mode.

By limp mode I mean I get the engine management light and it wont let me rev past 3k RPM.

 

[mirras]

Which sensor did they replace? I've recently replaced 2 on mine, the first one was the differential pressure sensor which cleared limp mode and engine management light ( after I reset the codes using a scantool ) then after a very long run ( just over 1000 miles ) I checked the codes again and had an O2 Sensor issue.

My code reader picked up P3002 ( which is still stored but not active )
P3013 , P2453 and P2454 .
Changing the differential pressure sensor cleared these and only cost £45 for the part.

After the long trip, which lightly sooted the rear bumper near the exhausts, I checked the codes again and got a P code ( which I can't remember ) relating to O2 sensor reading low, I bought a Bosch aftermarket one at £113 ( half the cost of the MB one ) and fitted that. All codes have now cleared ( except P3002 which is not active ) and the car appears to be running ok but I haven't been very far in it yet, I did have it MOT'd last week and emissions were fine.

I can only suggest you take it to your nearest specialist ( Automotive Solutions in Ayr or MercedesCarSpecialist at Ibrox ) and get a detailed diagnosis via STAR as you could end up spending a fortune chasing generic codes.

 

[MB8701]

Hi Mirras,

Thanks for your detailed reply.
That is the thing I am concerned about. I do not want to end up spending thousands on parts that are not needed.

Unfortunatly I do not know the exact details of what the diagnostics picked up however when I was having a quick glance at his laptop it did clearly only pick up one fault and he said with full confidence "DPF SENSOR" - he had put the bonnet into service mode (literally vertical) went towards the back of the engine and replacemend the DPF sensor there. The sensor looked like this as he showed it to me:

Exhaust DPF Pressure Sensor MERCEDES CDi 350 320 300 250 220 200 180 160 | eBay

The garage was knightswood service centre which seems to be highly rated on here - if they did not use STAR I would be very disappointed.

I am taking the car back monday for them to review the work they done but I may take it to Automotive Solutions in Ayr or Merparts which seems to be the holy grail of indys.

I would suspect if it may be something bigger however the fact the car runs flawless outside of this limp mode makes me suspicious its something small.

A regen of the DPF keeps poping into my head as the car has not been on a long run in years I think due to the last owner working away all the time.

I have done 700 miles since then and had a good few long runs and good spirited quick blasts but I dont think they were long enough and high enough in the rev range to kick in the DPF Regen. I read somewhere it needs to be about 3k RPM for approx 20/30 mins however this puppy sits around 1.7k RPM doing 80 on the M/W

 

[mirras]

That's the differential pressure sensor, mine showed an "implausible" value on the scantool from which I reckoned it was likely to be knackered. They apparently fail quite often but there are also a lot of folk suggest cleaning or replacing the pipes that supply it...

It's only a 20 minute job to change it out, I did my own, but cleaning the pipes out looks a bit harder to do...

 

[MB8701]

That's the differential pressure sensor, mine showed an "implausible" value on the scantool from which I reckoned it was likely to be knackered. They apparently fail quite often but there are also a lot of folk suggest cleaning or replacing the pipes that supply it...

It's only a 20 minute job to change it out, I did my own, but cleaning the pipes out looks a bit harder to do...

it diddnt look like a diffuclt job to me either but somehow the garage managed to extent the job time to 2 hours for this. No idea how!
Not happy if I am honest. That means my estimate of the job being a 120 pounds was more than fair.

When you say cleaning the pipes out - are you able to provide more information on what pipes. Also is there a good OBD reader I can buy? TBH if I could get a star diagnostics for around 300/400 I would. I think they are on ebay around 700 which is a bit much

 

[mirras]

I can only assume the pipes folk mean are the ones tucked behind the heat-shield where the sensor goes, I'm no expert, I just tinker. There is a thick and a thin hose connected the sensor, it's probably those. They were quite difficult to get to without taking a few more things apart. When I changed the O2 sensor it was caked in soot, not sure if that was a consequence of the differential sensor being broken, the cause of it being broken or not related at all.

I just use the Torque pro app on an android tablet with a cheap Bluetooth OBD2 adapter off eBay. I also have a Volvo C70 for which I do have access to the 'proper' tools. They cost £70 but STAR knockoffs are about 5 times the price for no obvious reason. I don't think I would trust them as I'm sure I could then 'fix it worse'.

 

[MB8701]

hi,

i think i might get a cheap obd reader just to keep handy.
i just noticed your in ayrshire - where abouts

 

[MB8701]

if it is only the DPF sensor showing as a fault code on the STAR then could it still be the turbo, manifold, inlet port shut off motor etc ?

I am assuming if only one fault code is showing for the DPF sensor then the problem must be related to this area only?

 

[Borys]

What is the mileage on the car?

 

[MB8701]

What is the mileage on the car?

41k

 

[Borys]

Very low miles, should be trouble free

 

[MB8701]

I had a chat with the guy today who replaced the DPF - he said he cleaned the lines a little when he swapped the DPF sensor however it was quite clogged up - he will give them a proper clean if I bring the car back in.

This sounds reasonable as the car as only ever done start stop driving in town for the last 3 years.

 

[MB8701]

Hi All,

I just thought I would update the thread as its very annoying when you are looking for same experiences and no one posts up how it ended.

I went back to stephen at knightswood service centre and he replaced to two pipes that go into the DPF sensor and all seems to be well now (fingers crossed)

It has only been a day but I am sure it will be fine - he had it up on STAR again and he flagged up the same fault and nothing else and after the pipe changes the STAR stored the fault with nothing else so happy days.

Stephen really is a great guy and I consider myself to be quite knowledgeable when it comes to cars but he really is a merc fan and knows them inside out which was a joy to see.

With that in mind I booked in a full service and a tranmission oil change as they are almost due anyway and just to keep the car in good order.

Hope this helps someone if they come across the same issue......