e93 320i - failed emissions test high CO reading

My neighbour's 2009 e93 320i with the n43 engine has just failed the emissions test in the NCT.

There were no errors showing in INPA or DIS. I did notice tat the reading from the O2 sensor after the CAT was showing a high voltage reading in INPA, see screen shot below.

http://i175.photobucket.com/albums/w...pslo0pzt8b.jpg

As a background to the problem the car previously had (a few months ago) a fault with a faulty NOX sensors and an intermittent failing ignition coil. not sure if this had a knock on impact on the O2 sensor.

I have a suspicion that the o2 sensor after the cat has failed causing the car to run too rich. I think it is part #2 in the diagram below.

http://i175.photobucket.com/albums/w...ps7jgnrpbm.png

BMWFans.info link to parts above:

http://bmwfans.info/parts-catalog/E93/Europe/320i-N43/R-N/dec2007/browse/exhaust_system/lambda_probe_fixings/

Anybody got any ideas, I don't want to recommend changing the O2 sensor unless it is actually the cause of the issue. They are about €200 OEM. An y help appreciated.

But it failed on HC? How mad it is ,HC? What is CO readings?

Lash diptane in it. Drive the bag out of it. Pass the test

As Valdas said take a screen shot of the actual readings.

Right, here's the readings:

It was actually the CO reading that it failed on:

Lambda 0.93
CO2 20 vol%
HC 156ppm

http://i175.photobucket.com/albums/w...psdjy3ch5k.jpg

Quote:

---

Originally Posted by rebel.ranter

Right, here's the readings:

It was actually the CO reading that it failed on:

Lambda 0.93
CO2 20 vol%
HC 156ppm

http://i175.photobucket.com/albums/w...psdjy3ch5k.jpg

---

See ,different story :)

I was going from memory, thought it was HC, but it was CO.