Audi A4 3.0TDi S-Line DPF Warning Light
Discussion
The DPF engine warning light appeared yesterday on my Audi A4 3.0 TDi S-Line Quattro. The vehicle has 66.5k miles & has just been serviced. Also the engine warning light has appeared in amber & a flashing squigly icon (normally for the glow-plug symbol).
The car appears to be in limp-mode, as it doesn't appear to perform as it should.
I rang my local Audi service centre this morning (Audi Harold Wood) & they recommened not to drive the vehicle & get it dropped off to them by the RAC.
I have heard that DPF replacements can be £1k +, so am a little worried as it's a twin turbo & may require 2 of them for each bank of the V6.
Audi said they need to run diagnostics on the car at £120 & then they will have a better idea of what is wrong...
Am I doing the right thing getting Audi to look into it, or should I go to an independent garage. I have heard of DPF cleaning, whereby they can be flushed through & re-fitted...
The car appears to be in limp-mode, as it doesn't appear to perform as it should.
I rang my local Audi service centre this morning (Audi Harold Wood) & they recommened not to drive the vehicle & get it dropped off to them by the RAC.
I have heard that DPF replacements can be £1k +, so am a little worried as it's a twin turbo & may require 2 of them for each bank of the V6.
Audi said they need to run diagnostics on the car at £120 & then they will have a better idea of what is wrong...
Am I doing the right thing getting Audi to look into it, or should I go to an independent garage. I have heard of DPF cleaning, whereby they can be flushed through & re-fitted...
It depends how far out of warranty it is and whether you've got a good relationship with your local dealer/whether they would be prepared to right your case for a contribution IF major parts need replacing. I'm not sure how Audi look at DPF failures, but I would assume they're not going to be offering much, if anything.
A good indy will be able to check for fault codes, confirm whether the ash loading on the DPF is such that a forced regeneration will clear it out or not, whether it can be removed and chemically cleaned, or if you're looking at a replacement. Guided fault finding in either indy or dealer case will lead them through the options, but cleaning may not be offered by a main dealer.
They are right to recommend you don't drive it - if the car has had multiple failed regens (which usually happens if you shut the car off while it's in the process of regening, or it simply fails to start) every time you start it it'll log another failed regen and eventually the damage won't be repairable via the forced regen option which requires steps by the dealer with the diagnostic kit plugged in to make it start.
Up to you where you take it, but I would suggest if it's not fixed after a forced regen (assuming that's what it needs) then you'd be looking at cleaning rather than replacement. They ought to be prepared to remove it and for you to send it away as needed, but best to be clear about your intentions as the car may be hanging around for a while.
A good indy will be able to check for fault codes, confirm whether the ash loading on the DPF is such that a forced regeneration will clear it out or not, whether it can be removed and chemically cleaned, or if you're looking at a replacement. Guided fault finding in either indy or dealer case will lead them through the options, but cleaning may not be offered by a main dealer.
They are right to recommend you don't drive it - if the car has had multiple failed regens (which usually happens if you shut the car off while it's in the process of regening, or it simply fails to start) every time you start it it'll log another failed regen and eventually the damage won't be repairable via the forced regen option which requires steps by the dealer with the diagnostic kit plugged in to make it start.
Up to you where you take it, but I would suggest if it's not fixed after a forced regen (assuming that's what it needs) then you'd be looking at cleaning rather than replacement. They ought to be prepared to remove it and for you to send it away as needed, but best to be clear about your intentions as the car may be hanging around for a while.
Hi Adrian - thanks for the information. The A4 is a 2009 model, so well out of manufacturers warranty. I purchased the car as used from Harold Wood Audi in July 2013 & it had a years warranty. Unfortunately this has now expired, so I'm a little concerned that I am facing a hefty bill.
I will ask Audi to provide a quote based on their findings & if it is too dear, will pursue the option of getting the DPF's flushed clean via a specialist.
I will ask Audi to provide a quote based on their findings & if it is too dear, will pursue the option of getting the DPF's flushed clean via a specialist.
I managed to get the problem resolved this evening (relief!). A mobile mechanic plugged his diagnostics computer into the A4 & has cleared the fault by re-genning the DPF's running the engine at a steady 2,000 revs for 40 mins. Once the computer is hooked up it keeps the revs steady to clear the issue. Cost = £60, a lot cheaper than Audi's diagnostics at £120!! So pleased now at full power & out of limp mode...
Did he tell you anything about the ash loading on the dpf to let you know how full it is? Even after a regen there's a residual ash loading that remains and is what forces more frequent attempts to regen. If you get the same fault again a clean would be the next step. Do you know how to recognise when a regen is happening when you're driving? If so, don't stop the engine until it's finished otherwise you'll get a failed regen and problems start. Also make sure you do some longer runs to give it a chance to clear out. Lots of short journeys will increase the loading on the dpf very quickly
Adrian pretty much covered it there; DPF issues with those are very uncommon unless horribly abused.
If it comes back I'd lean towards the sensor on the DPF rather than the filter itself. Don't even remember the last DPF replacement we did but the sensors can be finicky, they're cheap too.
If it comes back I'd lean towards the sensor on the DPF rather than the filter itself. Don't even remember the last DPF replacement we did but the sensors can be finicky, they're cheap too.
Hi Adrian - no I am not aware of the sign when the DPF is re-generating in the engine. I do normally take the car for 60 mile runs to Colchester every 2 weeks. I do however use the car locally & can understand how it can get coked up. The mechanic did check the ash content & it gave a reading of zero.
There may possibly be a fault with the sensors as on of the readings appeared as an error message.
Thanks so much for your advice. Unfortunately I have no experience of owning a car with a DPF before!
There may possibly be a fault with the sensors as on of the readings appeared as an error message.
Thanks so much for your advice. Unfortunately I have no experience of owning a car with a DPF before!
Hi Adrian - no I am not aware of the sign when the DPF is re-generating in the engine. I do normally take the car for 60 mile runs to Colchester every 2 weeks. I do however use the car locally & can understand how it can get coked up. The mechanic did check the ash content & it gave a reading of zero.
There may possibly be a fault with the sensors as on of the readings appeared as an error message.
Thanks so much for your advice. Unfortunately I have no experience of owning a car with a DPF before!
There may possibly be a fault with the sensors as on of the readings appeared as an error message.
Thanks so much for your advice. Unfortunately I have no experience of owning a car with a DPF before!
ChevyHead'68 said:
Hi Adrian - no I am not aware of the sign when the DPF is re-generating in the engine. I do normally take the car for 60 mile runs to Colchester every 2 weeks. I do however use the car locally & can understand how it can get coked up. The mechanic did check the ash content & it gave a reading of zero.
There may possibly be a fault with the sensors as on of the readings appeared as an error message.
Thanks so much for your advice. Unfortunately I have no experience of owning a car with a DPF before!
HiyaThere may possibly be a fault with the sensors as on of the readings appeared as an error message.
Thanks so much for your advice. Unfortunately I have no experience of owning a car with a DPF before!
The car will identify when it's being driven in a way that allows for regeneration to happen - so basically up to temperature, suitable engine speed etc, and looks at the loading on the DPF to decide if it 'needs' to regen. If it does, the ECU will inject more fuel into the exhaust which then generates heat in a diesel oxidation catalyst in front of the DPF. This additional heat will then convert the stored particulate into ash.
You may notice smoke from the exhaust, probably feel that the engine is working a bit harder/more laboured than usual, if you come to idle the engine will hold the revs higher than a normal idle. You're more likely to notice when it stops regeneration, as it'll feel like it's back to normal and will smooth out/give full power etc.
Whatever you do, if you feel it regenerating do not switch the engine off until it's finished. That's what usually causes problems.
Dr G mentions the sensors so if those were a stored fault get it changed. The pressure sensors either side of the DPF are what the ECU uses to determine whether the DPF needs to regenerate (the pressure differential indicates how 'loaded' the DPF is) so if one or both are faulty it may be trying to regen more than it needs to to try and avoid a clogged DPF.
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