Diesel Filter Replacement: When & How?

Hello, I'm new here and I have a question already.

Specifically, when should I change the filter, or how can I tell if it needs to be changed?
I have the impression that it's starting to produce more black smoke lately. I've observed other TDIs and noticed that they also produce a fair amount of black smoke. Is this normal for the 2.5 TDI with 115 hp, or what could be the cause? Otherwise, the performance seems normal.

Thank you for any advice.

Best regards,

Hello, what kind of engine do you have? Is it a 5-cylinder or a 6-cylinder?

I have an Audi with a 2.5-liter TDI 5-cylinder engine, engine code AAT.

Best regards,

Hello, the diesel filter is replaced every 60,000 km, but it is not the cause of smoke emissions; rather, it is more likely to cause a lack of power.
The air filter would definitely be a strong contender.
What about the start of injection?
Do you have a way to check this dynamically?
How many kilometers are on the engine?

Hello,

Regarding filter replacement:

Fuel filter replacement at 30,000 km.
Air filter: Replace every 60,000 km or 2 years.

I took this information from the Audi service manual (owner's manual). On the last pages of the service booklet, there is a list of all additional work performed, such as the air filter replacements, along with the corresponding mileage readings. At least, that's how it is in my service booklet.

The mileage intervals are the same in Etzold's book.


Oops, I was offline for too long, but you can still check the service book regarding the air filter replacement.

Best regards,

Hmm, that's strange.

mersente, how do you arrive at a figure of 60,000 km for the diesel filter?

Best regards,

'He mentioned that the filter should be changed every 30,000 km, and the air filter every 60,000 km. Well, I guess mine is probably overdue then. Mine is at approximately 50,000-60,000 km. Does the increased soot have nothing to do with that, or...? I personally can't imagine it, but you never know. Why could it be producing more soot/smoke? The oil looks good, and it's not consuming any. The last oil change was 5,000 km ago, and it hasn't gotten any better since then. The performance is still good. So, I would say everything is okay. But as I said, I have the impression that it has gotten worse. Could it also be due to the diesel fuel not being of the best quality?'

Best regards,

Hello,

A clogged diesel filter could lead to soot formation and increased fuel consumption in older mechanical pumps, because without sufficient fuel supply, the injection timing could no longer be adjusted early due to the lack of internal pressure. In TDIs, there should at least be a regulation difference (due to NOx emissions) in the error memory, as I imagine (I don't know if this is sufficient for limp-home mode, as I don't have a TDI, but if it is, you should be able to tell ).
The reason your engine is producing excessive smoke is likely due to the worn-out injectors.

Best regards, Uli.