Catalytic converter failure on Audi A3

Recently the emission light on my Audi A3 2.0 petrol came on. A couple of weeks later it went in for a main dealer service/MoT. They said they had done over 1 hour - £90 - worth of diagnostics and concluded the catalytic converter had failed. As a result, it would cost £1300 to replace.

They suggested it has structurally failed internally. The car is has covered 46,000 miles and is less than five years old. It has never had a misfire, a crash or driven through a flood. It has a 14 mile trip to work every day. Surely this part has not been manufactured to a proper standard?

After hearing this info, I asked the main dealer to put it through an MoT. It passed with the emissions light on. Can they be really sure the cat has failed? I

Asked on 30 July 2014 by Tymmy

Answered by Honest John
I don't think the cat converter has failed otherwise the engine could not have met the very specific emissions levels needed to pass the MoT test. What might have happened is that the engine has started to coke up around the inlet valves, which is common on these direct injection petrol engines because no fuel passes over the inlet valves to clean them. (That's why the latest EA888 2.0TFSI engine has indirect as well as direct injection.)

A probe inserted through one of the spark plug holes should find out. It can probably be cleaned up by the Terraclean process.
Similar questions
Is it illegal to de-cat a 2002 diesel Freelander TD4?
I own a 2005 Ford Fusion 1.4 manual petrol. It keeps losing power in second gear, accompanied by a burning smell. I heard two loud bangs in the rear of car as well.
What should the cost be for a new catalytic converter for a 2003 Peugeot 206 CC?
Related models
Good choice of engines. Some petrol engines now chain cam. Comfortable and well built interior. cheap to run 1.6 TDI. Feels very refined especially on the motorway.

Ask Honest John

Value my car