The Mégane II Owners' Club

Hi
Can the catalytic converter be removed permanently without the computer not liking it?
Stan

I think it's illegal to not have one in?

It is technically a legal requirement to have one when one is factory fitted. However, the diesels have only one emission test, when the oil temperature is above 60C. This is when the smoke test is performed. Because this test is not normally performed under load, there is little smoke.

Bottom line: it depends how friendly your MOT tester is.

Reference: https://www.motinfo.gov.uk/htdocs/m4s07000101.htm

I would also assume ...

That due to the undertray being on the car then the MOT tester wouldnt see the CAT, ( if it were there or not ) without removing the undertray or lifting the bonnet up first.

id be intrested to know youre outcome on the mot emmisions side also as im also thinking of removing my CAT, due to the shape and massive restriction it puts on the whole system, must lose a good wack of power.

Keep us posted !!

In South Africa we dont have to have the catalytic converter. In any case i have removed it and a Cat fooler was installed to fool the computer. Works like a dream and it has a bit more power..

Interesting. There was some talk about exhaust back pressure affecting the turbo a while back, but I can't remember the consensus on that. From memory I think the problem was debunked.

The insides of the converter was banged out thus the casing still remains, I beleive. Mot tests we dont have.

Me again. Mot, is it a test to check emmisions? We do have roadworthy tests.

In the UK (so far as I know) the MOT is an annual test that must be carried out on any vehicle over 3 years old. Basic mechanical, electrical and general roadworthy tests are carried out. Part of the test is to establish that the emissions are within whatever parameters are relevant to that car. Any defect results in a fail, and the car may not be driven on the road - until it is fixed.

The only emissions test on the diesel Megane that I know of is the smoke test. I doubt very much that hydrocarbon/CO and or other checks are made - nor would the presence or lack of be affected by the presence of a catalytic converter.

That is my opinion only. And, it depends on where you live of course.

"Sell it before it bankrupts you" I have had the Megane since new(2004), and the only problem we had was a glowplug in 2009 and now the turbo. Total costs R5400.00 (500 pound).

Hmm. So I could convert my CAT without failing MOT? Doesn't it smell without a working CAT or is it the build up that creates the smell?

Shanus1988 wrote:Hmm. So I could convert my CAT without failing MOT? Doesn't it smell without a working CAT or is it the build up that creates the smell?

Only you will be able to test that theory! As I said, the test relates to the jurisdiction you live in/under.

In the UK, only (as I believe) the smoke is tested at a fast idle. Remove/modify the CAT at your own discretion.