P0430 keeps returning after replacing multiple O2s and converter. What now??

[joefrog003]

Here's the scenario so far:

Got a P0430 code so I replaced the O2 sensor with a Denso model. Code retrurned a year later so I replaced the sensor again with another Denso. Code retruned within a month, so I took it to a muffler shop in town and they replaced the downstream drivers side converter. While he had that coverter off, he shined a light at the upstream converter and said it at least appeared to still be good. That was last week, and now today I just had the P0430 return.

Short of replacing the upstream manifold/converter, I'm at my wits end as to what to do next. Any ideas?

 

[4r-4ever]

yes, replace the first CAT or check if there are any leaks there.

 

[BlackWorksInc]

Have you had anyone with a scantool actually check what the fuel trims and sensor readings are for Bank 2?

 

[aemravan]

I could be wrong here... but my gut feeling is the muffler shop was just throwing an easy replacement on to see if it will fix the issue.. If you haven't replaced your upstream converter/header that is more than likely your culprit.

I do second the thought on scanning the fuel trims across both banks just to verify but am leaning highly towards a failing/old cat. If you're not looking to have it replaced you could always try the O2 spacer/spark plug nonfouler route to get the sensor out of the exhaust stream a bit to reduce the amount of reading it puts out. Has worked fine for me for the past year. There is a recent active thread on this around here some where. This would work considering that your upstream o2 sensor is fully functional and isn't causing screwed fuel trims.


ps: as a side note... not that I'm a exhaust technician or anything... but shining a light up the exhaust to evaluate the condition of a catalytic converter seems far from the best way to determine if its still efficient enough to fall within spec of what your ECU is looking for..

 

[Jmoore]

I just went through this exact scenario. I first replaced both drivers side a/f and O2 sensors. Code’s kept coming back after a month or so. Ended up replacing the manifold/cat with aftermarket. Still didn’t fix the problem. Replaced the aftermarket manifold with oem and now the code is finally gone.

 

[jmoore15]

Got screwed

I bought a V8 04 4runner from a guy and a week later the check engine light came on. mechanic says its the cats. I'm reading it could be the o2 sensors but I dont know if I want to spend the money i thats not it.

 

[4R005]

If I were you. I'll do the spark plug extender/O2 spacer route before throwing $$ into new sensors. Is/are codes P0420 or/and P0430 being displayed on scanner ? Codes can indicate a bad downstream cat or/and sensor. If engine operation and fuel consumption are normal then upstream cat and sensor are OK.
The SP/O2 spacers are $20.00 for a pair ( come in straight or 90 elbow choices ) in Amazon. Had a P0420 code 2 years ago in my '05 V8 4R. New O2 sensor did not fix. Went with SP extender, clear code, lites went away and still off presently.
If you're doing the work yourself, the biggest hurdle will be getting the sensor off ( rust ). Heat from a torch will be your friend. I lucked out with mine and O2 came out w/o heat use.

 

[4R005]

Just last week had CEL, VSC etc lites came on and P0430 code ( Bank 2 )when scanned. Had installed a spark plug spacer/extender on Bank 1 when I had a P0420 code previously ( #7 post ).
Check sensor with a known good unit ( a spare) and sensor was good. Installed an indentical spacer ( 90 degree ), cleared code. CEL and other lites went away. From previous experience remedial action was a fix if after 2 or 3 start cycles, lites remain off. So far so good. Will update if result prove otherwise. Had to heat sensor connecting fitting to dull red w/torch before it unscrew this time.

 

[MikeinNH67]

Just last week had CEL, VSC etc lites came on and P0430 code ( Bank 2 )when scanned. Had installed a spark plug spacer/extender on Bank 1 when I had a P0420 code previously ( #7 post ).
Check sensor with a known good unit ( a spare) and sensor was good. Installed an indentical spacer ( 90 degree ), cleared code. CEL and other lites went away. From previous experience remedial action was a fix if after 2 or 3 start cycles, lites remain off. So far so good. Will update if result prove otherwise. Had to heat sensor connecting fitting to dull red w/torch before it unscrew this time.

Where did you get the 90 degree spacers?

 

[dasx86]

I replaced the headers on my V8 with Doug Thorleys and had the issue. Turned out that where the driver's side SAIS tube on the header bolts to the upstream system had a leak. This connection is always under exhaust pressure, as it's downstream of the valve that opens and closes. Seems that extra oxygen was making it's way into the exhaust through there.

Going over the system with a stethoscope to confirm no leaks should be a prudent, easy first step before unloading the parts cannon IMO.

I will say that I could hear a leak in my system before remediating. If you're not hearing any leaks, perhaps this isn't a worthy avenue of investigation

 

[4R005]

Where did you get the 90 degree spacers?

Both straight and 90 deg elbows from Amazon. They came in packages of 2 pcs. I bought one package of each just in case I ran into space problems. Ended up using both 90 deg units, one each in Bank 1 & 2.

 

[4R005]

Here's the link for the 90 deg elbows https://www.amazon.ca/dp/B0CPYGB5Z5?ref_=ppx_hzod_title_dt_b_fed_asin_title_1_2

 

[MikeinNH67]

Here's the link for the 90 deg elbows https://www.amazon.ca/dp/B0CPYGB5Z5?ref_=ppx_hzod_title_dt_b_fed_asin_title_1_2

Ah, I didn't realize you were in Canada. Those don't seem to be an option in the US. Odd.

 

[4R005]

Ah, I didn't realize you were in Canada. Those don't seem to be an option in the US. Odd.

May need to Mcgyver a straight extender into a 90 deg and then some welding to complete.

 

[4R005]

Quick update on the P0430 code and subsequent SP extender installed just over a month ago. CEL and other lites still off after 50+ on/off start cycles. Keeping fingers crossed. Cheers and Happy New Year to all.