I am getting the following fault code on my 2005 4.2 SC

P0430-00 (E Catalyst system efficiency below threshold (bank 2)

If I clear it, it comes back after around 100miles or so. The date stamped on the catalytic converters is 2012 and the car has only done 87K miles and seems to be running fine, so it seems unlikely the catalytic converters would be at fault, so I'm guessing it is a faulty lambda sensor, but I can't figure out from this code which one it would be.

Grateful if anybody point me in the right direction.

My fallback otherwise is to buy one and systematically swap each in turn, assuming they are all the same. From looking at the car the connectors look the same, but the post cat connector wires look longer. So hopefully buying one of these would be good enough.

Regards,
Ian.

Does this help if you can manage to read it, not a very good print.



Cheers
Col

thanks Col, this is all I had managed to find too. It looks a bit extreme in terms of approach including changing the catalytic converters. I'm fairly sure it is a lambda sensor. You would have thought the error code would make it obvious which one, but doesn't seem like that.

The engine banks are A - right, B - left. Might be reasonable to assume that Bank A = Bank 1 and Bank B = Bank 2 in the error codes. Left and right are when sitting in the car facing forwards I believe.

There are 4 sensors in total, two sensors per side, one each before and after the catalysts. 2012 SDV6 - it's missing a couple of cylinders
2008 TDV8 - it was a labour of love and is much missed

To try and confirm i've identified the right one, I swapped the bank 1 and 2 post cat sensors over today so waiting to see if the fault reoccurs on the other bank.

Today I got the same fault code back. That's after a couple of weeks and a few hundred miles with no issue. I was rather hoping that if the fault came back it would be on the other bank having swapped over the sensors, apparently not.

What I have noticed is that the fault only ever occurs (so far) when I've been driving at a constant speed on the motorway for some time. Don't know what to make of that. Grateful if anyone has any ideas ?

I have just got myself the IIDTool but unfortunately that doesn't enable monitoring of cats and it's not found any other issues.

I have now noticed that on bank with the trouble the pre cat sensor looks quite new, so maybe it is more efficient / sensitive than older ones. May be clutching at straws but the cats are fairly new and the car seems to be running fine. Anyhow I've just ordered a new sensor and with fingers crossed will try again.

If it was a lambda Spenser it would say so in the fault code ie bank 1 sensor 1 or sensor 2 depending. Sensor 1 being pre cat. 2008 G4 RRSport TDV8 current
2009 TDCi 90 current
2018 Discovery 5 HSE lux current
1994 Dakar current

Same thing happened to me today. Car driving fine though. Very old thread I know, but I'm curious if OP managed to work out what was up?

Yes, I fixed it. Unfortunately by fitting a new cat. had a local garage make for me at a reasonable price.

Thanks for replying. Shame it wasn't just a sensor. Did the issue ever affect the car or put it into restricted performance mode? Or did you just get EML over and over?