MoT failure query
 

Considering buying another v6. One that interests me nearby has this frequent MoT failure (well thrice in the past six years). What may be the cause and solution?

"Exhaust carbon monoxide content after 2nd fast idle exceeds manufacturer's specified limits (8.2.1.2 (a))"

Two factors cause this. A failed catalytic converter won't reduce what CO is generated to the required level. The CO level can also be too high due to poor combustion. This relates to the air/fuel ratio as controlled by the ECU. The level in the exhaust gas before entering the catalyst is typically1% or so, which is converted to carbon dioxide within the catalytic converter. A T4 session may identify poor fuelling. The need for a catalytic converter replacement is quite likely I'd say.


TC

Whats the service history like? Worn plugs, old engine oil and a filthy air filter would be a factor. Plus if its done short journeys the car could just need a decent blast with a good fuel system cleaner such as cataclean.;)

Assuming this to be the worst case scenario. Pricey?

The original MGR catalysts were. You can now buy a decent 75 for what Xpart/Rimmer once charged. Catalytic converter prices vary widely like anything else car-shaped. Basically, you usually get what you pay for. Rimmer price is currently £220 for an OEM alternative. Maybe try DMGRS?


Xpart/Rimmer: https://rimmerbros.com/Item--i-GRID001949


TC

My car stood for 2 years and did/does short trips. I have been advised a blast at low revs with Cataclean in might help. Hust running fuel down enough this week to do it this weekend! ☺

Put a bottle of cataclean in Moonstone last week before a blast down the motorway to nano meet. Going for MOT tomorrow, will see what happens!

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Martin.
Give it a good hard run about 30 minutes before your MOT allowing you to then turn up 5 minutes before your appointment place with a nice hot engine it will pass the exhaust test easy.

As Arctic says, catalytic converters need to be hot - so a good 'Italian tune up' is usually enough to get the emissions within limits. :D

That's why my car nearly failed - took it nice and hot but they parked it up from 2pm to 5.15pm before testing! I think it definitely needs a good blast as well with how its not been used enough.