e93 320i - failed emissions test high CO reading

[rebel.ranter]

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.



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.



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.

[Valdelisbmw]

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

[JohnC]

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

[HealyC]

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

[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

[Valdelisbmw]

Right, here's the readings:

It was actually the CO reading that it failed on:

Lambda 0.93
CO2 20 vol%
HC 156ppm

See ,different story

[rebel.ranter]

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