97 bmw m3 p0430

[m3f_likwidmonster]

Hello. I have a 1997 BMW M3 with 138k miles and I recently had a p0430 come up. I replaced the downstream o2 sensor and then about a week later after driving spiritedly I had the code come back on again.



It seems to be due to the CAT but I haven't noticed any performance issues except a slight misfire at cold start and at times when I try to rev during the misfire it will stall out a little. Otherwise it drives and performs totally fine.



I am currently on a 10 day state inspection and need it to pass for now. Has anyone had luck with using the spark plug defoulers?



Any suggestions?

[m3f_bluptgm3]

How about fresh plugs and plug/coil extenders? Have they ever been replaced?


What are your driving habits?


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[m3f_likwidmonster]

I replaced the coils about 3 years ago and it's been driven close to 10k miles.



I replaced just the passenger bank 2 oxygen sensor a week ago.



I don't typically drive it hard and usually drive it while shifting at 3500-4000 rpm without accelerating hard.

[m3f_M_Parallel]

What's with these P-codes? I've never seen any P-codes listed during any of my diagnostics seasions.

[m3f_likwidmonster]

The p codes come from a generic obd scanner.



The p0430 represents Catalyst System Efficiency Below Threshold (Bank 2)

[m3f_M_Parallel]

Getting an Inpa install and BMW cable is so cheap nowadays, why bother?


But if it does the job, ok I guess.

[m3f_likwidmonster]

In years past I had a cable but lent to someone who never returned it... Guess I learned my lesson on that one.



For now, I just ended up using a spark plug defouler to get it to clear.



I am looking for other midpipe solutions for after this inspection.



I keep hearing people to tell me to gut the cats. Any thoughts?

[m3f_bluptgm3]

Gutting the cats is not going to solve this issue.

You could purchase the post catalyst O2 sensors simulators being sold on this vbb for now and sort out your catalyst issue later.


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[m3f_likwidmonster]

Gutting the cats is not going to solve this issue.

You could purchase the post catalyst O2 sensors simulators being sold on this vbb for now and sort out your catalyst issue later.







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I appreciate the response!



I do understand that gutting the cats will not solve this. So far I have temporarily solved this issue using the sparkplug defoulers (creates a gap between the oxygen sensor and cat).



I was just looking for the opinion of other users about gutting the cats and then installing the simulators as you stated above.

[m3f_dallasbrandt]

Just a shot in the dark, but how about "rebuilding" the injectors. This I mean by replacing the little filters and external seals on the injectors. Super cheap and quite easy, maybe you got a clog and causing a running issue.


It made my M3 run better, and I had no symptoms, I just wanted to do it.


Now that I know this, it will be where I start on any running condition because it is cheap and easy... as well as spark plugs

[m3f_S4Sprint]

How cheap is the injector rebuilding?

[m3f_englishtom1596q]

Just a shot in the dark, but how about "rebuilding" the injectors. This I mean by replacing the little filters and external seals on the injectors. Super cheap and quite easy, maybe you got a clog and causing a running issue.



It made my M3 run better, and I had no symptoms, I just wanted to do it.



Now that I know this, it will be where I start on any running condition because it is cheap and easy... as well as spark plugs

That would be picked up on upstream O2 sensors, not downstream. Downstream sensor measure how well the Cats are doing their jobs. Upstream control fuel/air ratio via injector duty cycles.

[m3f_Jawse36]

Generally speaking, catalyst efficiency codes are indicative of catalyst failure. Unfortunately this prob means replacement of the catalyst is necessary. If that's the case, look aftermarket because a factory catalyst will cost an arm and a leg.


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