NCT: Failing emissions

KizzyMonster

05 BMW 1 Series failed NCT with High Idle C of 0.38% (Needs to be less than 0.2).
Mechanic gave full service, changed sparks etc but it only went down to 0.27%.

He reccomended dipthene, will this work?
One of the lads in work reccomended driving on the motorway in third gear before the test also, are these alll old wives tales or is there actually a way to pass the test?

Where can I buy dipthene in Galway?

biko

You can buy Dipetane in Halfords or motor factors

Atlantic Dawn

Yes that should help as should driving in a low gear. Another tip is to not sit parked up with the engine running at the NCT centre, this can skew figures too, just park it and shut off engine.

Cosmo K

Why do people still recommend this stuff? Dipetane is not the miracle cure people say it is.

punisher5112

Drive the nuts out of it. Give it some good runs to get it all cleared out.

jimgoose

What is the full set of emissions readings?

Fundthementals

Assuming lambda reading is ok - I would suspect you need a new CAT.

shawnee

Well of course people are recommending it if it works. Had a friend who's beemer failed the emissions twice and felt he would need to get rid of the car. Added the red stuff two days before and it passed on third attempt.

Dipetane "works" on diesels if you are just above the limit as burning this stuff doesn't produce any soot plus if you drive it like you stole it after adding the snake oil in the tank clear all the accumulated dirt in the engine and it would probably pass even without it.

But, in general, it would be better to actually fix the issue that cause your diesel to fail. My 15 y.o. Sprinter CDi with 220k miles on clock without any emission controls (vans of that age didn't even have egr) after driving like you stole has a smoke value of 0.4 (3.5 allowed). If your modern soot box registers over 3.5 you need to get it fixed!