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BMW E46 318i 2000 - Code P0420 Cat Converter Conversion #

Posted by Sean Murphy on October 3, 2012, 3:45 pm

Year of Manufacture *: 2000
Engine Size and Code *: 1.9
( Optional ) Scanner Used: Autologic

Hi all,

Have this car in with a "P0420 Catalytic Converter Conversion" fault.

If you reset the error it drives for a week or so fine, and then will trip the EML and log this fault. Its been to another garage and already had a new [aftermarket] catalyst and NTK post-cat O2 sensor but still the fault occurs. We've smoke-tested the intake and all is OK, smooth running values look ok.

Autologic fault reported as:

(165) A5 EUIII code p0420 Catalytic converter conversion
Currently present
Fault is not sporadic
Undetected for 48 times
IMPLAUSIBLE VALUE

Anybody come across this before and have any ideas where to look? Thanks.

Re: BMW E46 318i - P0420 Cat Converter Conversion

Posted by Glyn Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on October 3, 2012, 5:19 pm, in reply to "BMW E46 318i - P0420 Cat Converter Conversion"
Glyn Morgan

Hi Sean,

Scope pre & post O2 sensors.

What are the fuel trims in your freeze frame data ?

Regards Glyn

Re: BMW E46 318i - P0420 Cat Converter Conversion

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on October 3, 2012, 5:57 pm, in reply to "Re: BMW E46 318i - P0420 Cat Converter Conversion"
Peter Mutlow

.......and what are the 4 gas emissions at normal and fast idle?

Regards

Pete M

Re: BMW E46 318i - P0420 Cat Converter Conversion

Posted by Glyn Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on October 3, 2012, 7:06 pm, in reply to "Re: BMW E46 318i - P0420 Cat Converter Conversion"
Glyn Morgan

Hi Pete,

.......and what are the 4 gas emissions at normal and fast idle?

Now where have I read that before

Re: BMW E46 318i - P0420 Cat Converter Conversion

Posted by Pete Mutlow <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1569' width='330' height='300' border=0 style='border:none;'> on October 3, 2012, 8:46 pm, in reply to "Re: BMW E46 318i - P0420 Cat Converter Conversion"
Peter Mutlow

Hi Gyn,

*Now where have I read that before*

Where it has been omitted!

Regards

Pete M

Re: BMW E46 318i - P0420 Cat Converter Conversion

Posted by Sean Murphy <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT1788' width='330' height='300' border=0 style='border:none;'> on October 4, 2012, 7:19 pm, in reply to "Re: BMW E46 318i - P0420 Cat Converter Conversion"

Bloody emissions kit went up the creek this morning so i've no idea what they are at the moment (kind of goes with the rest of the luck i've had this week!).

Someone has said that the non-oem cat could be the cause - what's your thoughts on that (its got a Klarius one on it at the moment)?

Car isnt coming back till Monday now so if there's any ideas between now and then let me know!!

Re: BMW E46 318i - P0420 Cat Converter Conversion

Posted by Glyn Morgan <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2543' width='330' height='300' border=0 style='border:none;'> on October 5, 2012, 1:09 pm, in reply to "Re: BMW E46 318i - P0420 Cat Converter Conversion"
Glyn Morgan

Hi Sean,

Someone has said that the non-oem cat could be the cause - what's your thoughts on that (its got a Klarius one on it at the moment)?

That is a possibility, but if you scope both O2 sensors ( or even use two multimeters ) you can prove the fault.

Regards Glyn

Re: BMW E46 318i 2000 - Code P0420 Cat Converter Conversion #

Posted by Mark Storey <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT5564' width='330' height='300' border=0 style='border:none;'> on October 5, 2012, 6:36 pm, in reply to "BMW E46 318i 2000 - Code P0420 Cat Converter Conversion #"

P0420 is a converter efficiency code.
Unless the fueling is up the spout I'd be chucking the non-OE Cat in the bin.

Hth
Mark

Re: BMW E46 318i 2000 - Code P0420 Cat Converter Conversion #

Posted by Dave Hill <iframe src='https://members5.boardhost.com/ukautotalk4/info/user=UKAT2783' width='330' height='300' border=0 style='border:none;'> on October 7, 2012, 7:59 pm, in reply to "Re: BMW E46 318i 2000 - Code P0420 Cat Converter Conversion #"

Hi Sean

Almost without exception, every example of "P0420 Catalyst efficiency bellow threshold" that I have seen, has been accurate, in as much that the PCM has assessed the catalyst performance accurately.

Of course you have to look for any underlying issues, that might cause a new catalyst to fail, but it has to be said that you can place zero confidence in any aftermarket product. The introduction of "type approved catalysts" has done little to improve the situation.

Take a look here for some testing tips.....

HTH

Link: Catalyst Efficiency The Pico Way

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