2001 BMW X5 P0430 Please help!!!
 

I have been getting P0430 about once a while after I reset couple of months ago. This past week again, I have gotten the P0430 and my 2001 X5 with 3.0L had 200K miles on it. My car runs great. Acceleration is good, no rattles from underneath, no indication that anything is wrong except for the CEL. I replaced the both post-cat and precat oxygen sensors about 6 months ago with a new Bosch sensors and also replaced sparks plug and ignition coils.

Thanks,
Henry

I googled "BMW OBD II PO430" and got this:
OBD-II Trouble Code: P0430 Catalyst Efficiency Below Threshold (Bank 2)
P0430 BMW Catalytic Converter Conversion 2 OBDII Engine Light Trouble Code | Engine-Codes.com

Take note of the things mentioned under "causes"... it appears that there are more causes listed than the ones you mentioned that you changed/replaced.

P0430 and it's brother, P0420, are often taken as signs the catalytic converter is bad. What it really means is the converter is not able to digest the exhaust, which can be the result of a bad converter oxy sensors, or an exhaust leak. Since the cat/converter's life expectancy is around 20 years it makes sense to rule everything else out first.

Remember, an exhaust leak will produce a P0430 code, too.

Good luck. :)

Henry, I too have been getting P0430 on an otherwise well running 3.0 with 178K. The code first popped up last summer and the guy at Autozone told me they read that code quite often on customer's cars and he recommended running fuel system cleaner. I suspected he was just trying to make a sell but it worked and the code never returned until a few weeks ago. A couple of weeks before that I had rebuilt my DISA value and replaced both pre O2 sensors for routine maintenance and my engine is running great with even much improved gas mileage but now that pesky P0430 is back and fuel system cleaner didn't help this time around. My cat(s) seems solid and I'm sure hoping they're not needing repla$ed. I thought about getting new post O2 sensors but I'm seeing that didn't remedy your code.

I think I'll double check carefully for a potential exhaust leak.

Hi, I have a 2002 BMW X5 3.0i and my problem is real interesting. I am getting a P0430 (Bank 2) code too, but when I swap the two A/F (upstream pre cat) sensors the problem swaps to the P0420(Bank 1). Obviously I bought a replacement, Bosch 13477 A/F sensor on Amazon and swapped it out with the sensor I figured was operating poorly. The new one in,... and still got the code. Got another one (replacement as I thought they sent me a bad new one) and same problem.

What is seriously odd is that the used sensor that doesn't trigger the code, no matter what Bank I put that one in, no code, ONLY in the other bank with the "new" sensor does the SES light come on. I don't see how it could be anything beyond the sensor... BUT it's NOT the CATs or they would trigger no matter what sensor is in... right?!

Can't be the CAT or it would show up on the same bank.
Two new bad sensors? what are the odds?

Did you fix it? I had the P0430 keeps coming up after clearing but the secondary air system readiness will not come up. So after some testing I removed the secondary air valve and cleaned it with throttle cleaner thoroughly. The CEL code cleared 24 hrs later and all IM readiness is green.
I'm going to change the valve anyway as there's a lot of carbon.

Don't think your ever going to get an answer from this poster as he posted once and gone.... RnRmaCHine

Make sure you replace the vacuum line to the air pump valve. It runs behind the valve cover near the firewall. This line fails frequently.