2005 Polo NCT Emissions Failure

zippyddog

Hi All,

I Just put 2005 Polo 1.2 (3 Cyl) Petrol through the NCT, and it failed on CO Emissions. Car has 200Kms on it.

Low Idle CO 0.31 Vol% (Limit is 0.30)

High Idle CO 0.55 Vol% (Limit is 0.20)

I have attached the NCT Report for reference on other the other Emissions readings.

I get a fairly infrequent P0420 Engine Code, indicating Catalyst System inefficiency (Catalytic Converter??).

I was also getting an P0116 during the winter months, which pointed at the coolant Sensor. I changed the Sensor but that Code still crops up occasionally. So perhaps a Thermostat/thermostat Body issue?

Generally Car is running fine, the exhaust perhaps blowing a tiny bit, only noticeable when idling. It had an oil/Filter Change recently, but I didn't change Plugs or Air filter this time around.

I got a quote for €350 for a CAT replacement, but just wondering if there are any other things to check/diagnose before I shell out on this?

Cheers!!

John.G

Well worth trying a new set of plugs, nothing fancy, <€20, I always install new plugs just before the NCT on the same car/engine (daughters) with almost identical kms, plugs+retest will still cost < €50.

mk7r

https://www.boards.ie/discussion/comment/119177292#Comment_119177292

Plugs will only affect the HC readings not the CO. This is a safe enough bet for a new cat

zippyddog

thanks @John.G and @mk7r for replying..

I actually brought it to a local service shop and they suggested that before I invest in a new CAT that I should try using Dipetane leading up to the test and to bring it in to the test centre with the Engine Hot.

And It passed ! :)

I have continued to use Dipetane regularly since and strangely the P0420 Error Code hasn't cropped up again.