EGR fault

[chiefsittingduck]

Hi all, my first post here!!i have recently bought a 2015 C200 Blue tec with a 1.6 diesel engine - Renault so i'm told?? the engine management light comes and goes roughly a week at a time - (it was off when i bought it!!) its currently on and as i use it on the motorway a lot i'm constantly worried something will happen. i have been told and seen the ERG valve has been replaced which the diagnostics show as being the fault.
The car runs fine but i do notice sometimes that its holding back and slightly fluctuating on revs - it can restrict power a bit too...

Any ideas if there could be something else apart from ERG valve? faulty ERG?

thanks in advance

 

[Larkone]

As always with MBs the best solution is to get some proper diagnostics from STAR - MBs diag tool. Some one will probably be able to recommend an indy in Devon rather than the high cost of the main stealers.

 

[chiefsittingduck]

hi all - took car back to the garage that changed the EGR initially and they hooked it up to the star system(apparently it hasn.t been called that for years!) the only error message was a faulty with EGR so they rest the system - apparently this is telling the engine there is a new part fitted so the engine management can carry on as normal - this worked great for a couple days - the car drove great no holding back, no fluctuating and no over revving at 3-4k rpm - it was lovely. then the light came back on and the issues started again... grrrr.
any thoughts on what else it could be? is there a plug or switch it could be? or is it a faulty EGR??

 

[Supernoodle]

If you're getting a fault it would be helpful to mention what it is.

 

[chiefsittingduck]

If you're getting a fault it would be helpful to mention what it is.

not being funny but if i knew what the fault was i wouldn't be asking if anyone knows what the fault could be? ive explained the symptoms and explained that the car runs great after its been reset and mentioned its had the EGR valve replaced? tell me what other info you need and i'll try and provide.

 

[m80]

It has been reset, so there will have been fault code/s.
Fault codes can be a valuable pointer.

 

[Drewski09]

What fault are you getting ?

 

[chiefsittingduck]

It has been reset, so there will have been fault code/s.
Fault codes can be a valuable pointer.

ok thanks, whilst i dont at present know the error code i have been told it was an EGR flow issue - low pressure so it had a new valve fitted and the system had been cleaned - hope this helps?

 

[Supernoodle]

not being funny but if i knew what the fault was i wouldn't be asking if anyone knows what the fault could be? ive explained the symptoms and explained that the car runs great after its been reset and mentioned its had the EGR valve replaced? tell me what other info you need and i'll try and provide.

If you have a MIL light you have a fault code.
If you have a code there should be snapshot/freeze frame data too that gives some data at time of fault setting.

 

[chiefsittingduck]

ok thanks, whilst i dont at present know the error code i have been told it was an EGR flow issue - low pressure so it had a new valve fitted and the system had been cleaned - hope this helps?

 

[chiefsittingduck]

If you have a MIL light you have a fault code.
If you have a code there should be snapshot/freeze frame data too that gives some data at time of fault setting.

ok thanks! im afraid ive no code and wasn't given a snap shot - i have asked the garage for the info or i may have to go back again and re do it!
Such a shame as the car runs lovely prior to the MIL coming on - it feels as if the car is holding back at times and will also gently judder at speed. when it changes gear it can rev like hell between 3-4k rpm before settling into gear!

 

[Supernoodle]

It's crucial to understand why the ECU sets the fault. Just because it mentions a component doesn't necessarily mean that part is faulty.
EGR isn't directly measured, but inferred from the MAF. When the EGR is requested, ECU expects to see a corresponding reduction in the MAF. If that reduction isn't seen it will set a low flow fault.

Assuming the error is low flow. The LP EGR on that engine (at least when used in a Nissan) has a cooler that could get blocked. In the exhaust there is a valve, used to increase back pressure thereby increasing flow through the LP EGR. Something else to check.
It also assumes the MAF is reliable and probably is otherwise you'd have other faults.

So plenty to check and test before you just replace parts.

 

[chiefsittingduck]

It's crucial to understand why the ECU sets the fault. Just because it mentions a component doesn't necessarily mean that part is faulty.
EGR isn't directly measured, but inferred from the MAF. When the EGR is requested, ECU expects to see a corresponding reduction in the MAF. If that reduction isn't seen it will set a low flow fault.

Assuming the error is low flow. The LP EGR on that engine (at least when used in a Nissan) has a cooler that could get blocked. In the exhaust there is a valve, used to increase back pressure thereby increasing flow through the LP EGR. Something else to check.
It also assumes the MAF is reliable and probably is otherwise you'd have other faults.

So plenty to check and test before you just replace parts.

excellent thankyou for the reply! i was thinking could it be something else so i will investigate further! is the cooler and valve in the exhaust something i can access an check myself?