Author Topic: A4 B6 damaged cats causing fuel inefficiency?  (Read 812 times)

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Offline A4RD

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A4 B6 damaged cats causing fuel inefficiency?
« on: June 08, 2021, 01:03:20 pm »
Hey team,

Wow so glad to find this forum!

Hey so I have two A4 B6 Quattro Avants... and because i'm a pillock who never learns, I fear i've done the same thing to each, which was hit a speed hump too fast and, I suspect, damaged the cats. Ever since my fuel is depleting super quick... the instrument panel is showing 10.5l per 100km being used, and my obd scanner ain't connecting so i'm left to speculate.  Does this sound right to any of you more mechanically minded A4 owners?

On one of the cars, the one with the ASN engine, it's led to misfires on cylinder 2.  I've replaced coils, but probably now need to replace spark plugs too, and I fear.. o2 sensor and/or cats.

Is it a difficult thing to remove the cats entirely?  I've read somewhere that you need to drop the subframe and that's already beyond scope for me.

Are there other suggestions I might try first?

I'm trying to get these cars both working mint again because they're amazing, and also because it appears I have to sell them to clear a $5k lawyers bill that just blindsided me.


Offline GLIDN

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Re: A4 B6 damaged cats causing fuel inefficiency?
« Reply #1 on: June 14, 2021, 11:44:46 am »
CAT is attached by the Turbo, so subframe removal is not required, it could make the job a little easier. If bolts are seized on.
More likely a leaking exhaust or faulty 02 Sensor or Airflow sensor.
Audi A4 DTM - Stock NZ New | All servicing done | Carbon Clean done
Gone - VW Tiguan | APR Stage 1 | Stage 2 DSG | Tuned by HSP Tuning

Offline A4RD

  • Posts: 3
Re: A4 B6 damaged cats causing fuel inefficiency?
« Reply #2 on: June 15, 2021, 12:46:51 pm »
thanks for your reply. appreciated.  I'm going to try replace the o2 sensors and see if that corrects my issues.