Need help with OBD code P0430

[Cashcrazy]

2011 Explorer, 108k. The check engine light recently came on my Explorer, code P0430 - Catalyst System Efficiency Below Threshold (Bank 2). After some online the research the easy signs pointed to the downstream O2 sensor on bank two. I replaced both downstream sensors and reset the codes. It threw the code again after a long test drive. My next step was to connect with FORScan. I compared the voltage on both of the downstream sensors and what I noticed was the bank 2 downstream sensor voltage was jumping up and down while the bank 1 downstream sensor was staying fairly consistent during steady highway speeds. Has anyone ran into this same issue or know what the bouncing voltage means? Thanks in advance.

 

[Flying68]

A quick Google search says that it indicates a failure of the catalyst system. Further reading says that if is the only code present, check for exhaust leaks both up and down from the cat. If those are fine the likely cause is an obstructed cat. You have already replaced the O2 sensor.

 

[bigdude2468]

I would flip the two O2 sensors side to side to confirm that you don't have a bad sensor. Replacing a CAT is expensive, flipping them is easy especially since you just had them out. Remember NEW means "never ever worked"

 

[stuarto]

Hi @Cashcrazy
Take a look here : P0420 and P0430 Codes

I posted a workaround that you may be interested in.

 

[Crates]

I recently worked on a vehicle which was throwing the same 0430 code, what I found was a leak due to a fatigue crack in the flex joint just downstream of the oxygen sensor. The crack was small enough that you couldn’t hear it but it allowed air into the exhaust system and it was causing the sensors to flag the 0430 code. Tried welding it but it was practically tin foil so I ordered him a new pipe. Problem solved.

 

[peterk9]

I recently worked on a vehicle which was throwing the same 0430 code, what I found was a leak due to a fatigue crack in the flex joint just downstream of the oxygen sensor. The crack was small enough that you couldn’t hear it but it allowed air into the exhaust system and it was causing the sensors to flag the 0430 code. Tried welding it but it was practically tin foil so I ordered him a new pipe. Problem solved.

Sounds like this issue; 2013 limited front exhaust pipe break (by flex joint), what to do... Member had it fixed at a muffler shop.

Peter

 

[Crates]

I forgot to mention, the exhaust leak would also tie in with the bank 2 sensor voltage bouncing around.

Let us know what you find.

 

[Cashcrazy]

Forgive my slow response. For some reason I did not receive the normal email notification for the replies. I had to send it to the shop today for AC work. I will look for a crack in the exhaust pipe when I get it back and post an update. I appreciate everyone’s help with this issue.

 

[Cashcrazy]

I recently worked on a vehicle which was throwing the same 0430 code, what I found was a leak due to a fatigue crack in the flex joint just downstream of the oxygen sensor. The crack was small enough that you couldn’t hear it but it allowed air into the exhaust system and it was causing the sensors to flag the 0430 code. Tried welding it but it was practically tin foil so I ordered him a new pipe. Problem solved.

Was this crack between the upstream and downstream sensors or after the downstream?

 

[Crates]

On the one I worked on it was ~ an inch downstream from the primary oxygen sensor at the flex joint.

 

[Cashcrazy]

I looked and listened for an exhaust leak and couldn’t find anything. Does anyone have the service manual with the catalytic converter bolt torque specs? It looks to have six total bolts.

 

[KayGee]

Best way to identify exhaust leaks is with a smoke machine (~$100-150). https://www.amazon.com/AutoLine-Pro...coding=UTF8&psc=1&refRID=KT1KT25HY4G9YC7JN1ST https://www.amazon.com/Detector-Exhaust-Intake-Adapter-Diagnostics/dp/B077TKTPLL

Alternative, if you are up for it, is with a shop vac and a spray bottle of soapy water. How to Diagnose Exhaust Leaks With a Shop-Vac

 

[Cashcrazy]

I had a smoke test ran on it and no leaks were found. That is ultimately why I decided to replace the catalytic converter.

 

[JohnelP]

Hi,

about 3 weeks ago check engine light came on with the error code P0430 (Catalyst system efficiency below threshold (Bank 2)). after two days it got off itself. Until the day before yesterday, when came back. I installed the FORScan and got the ODBLINk EX. tested the car this morning, and the i have the same code as last time.

I see the troubleshooting sequence is O2 sensors, Exhaust leak, MAF sensor and the Cat converter itself.
I used the ForScan to read the O2 sensors voltages(impedances). I have 0.1V ~continuously for 1st sensor (upstream) on both banks 1&2. Both downstream (2nd sensor) on both banks 1&2 were showing about 0.9V when steady engine RPM, and vary anywhere between 0.1V and 0.8V when sharply change the rpm of the engine (pulsating ON-OFF the accelerator pedal).
As said, both 2nd (downstream) O2 sensors (bank 1 and 2) we synched showing more or less same value all the time. That's giving me the hint the O2 sensors are fine.
In the readings, I see there is a measurement for the CAT temperature. But I see it was read at sensor 1. It showed about 400 to 500 degrees Celsius. Steady and similar on both Banks 1 and 2. Not sure if they measure the CAT temperature at sensor 1 port, or the heated sensor itself (I assume they should have same temp once engine warms up?)
I do not hear any extra noise, and I do not feel any power loss.

My thoughts:
MAF sensor unlikely bad. Given it is on intake path, I assume a faulty MAF should trigger errors on both Bank 1 and 2, not just bank2.
O2 sensors seem to work, and given the correlated values of the sensors readings between two banks. So, I would postpone the blame on the O2 sensors.
Exhaust leak - I could not hear any different noise.
Cat Converter - I recall on my old car (4 cyl only + turbo), when the cat converter got clogged, the car lost its power (barely moving), and the turbo was "close to melting" - glowing red. My explorer does not have turbo, but given I do not feel power loss - again, I cannot say how it feels in term of power loss if bank2 cat gets clogged bur cat on bank1 continues to work. My old car was more straight forward; it did not have two exhaust paths. Taking into consideration the CAT temperature readings being equal on both banks, puzzles me a bit.

Can it be that cat converter to get clogged /unclogged as the wafers are shaken during driving? Or once it gets clogged, stays clogged?
I would rule out the cat lost its efficiency, as the measurements are identical on both bank1 and 2.
Ideas?

 

[JohnelP]

Reading a bit on what values should be, and it seems the first sensor must fluctuate between 0.1V to 0.9V, and the second should be almost steady around 0.45V.
I need to check the readings/values at 2k rpm, as i measured mostly at idle.

I understand I may face a vacuum leak...as 0.1V on 1st sensor indicated lean mixture.... and banks have identical behaviour, and both bad.

 

[peterk9]

^^ Your thread was merged with this one on the same issue. I don't know if this thread is helpful? Fix P0420 P0430 for only 10$

Peter

 

[JohnelP]

^^ Your thread was merged with this one on the same issue. I don't know if this thread is helpful? Fix P0420 P0430 for only 10$

Peter

Yes, I am suspecting a vacuum leak too. As both 1st sensors stay locked at 0.1V -> make me think engine runs lean. No matter the rpm.
And it seems they do not enter the closed loop, gets locked lean.
Since it happens on both banks, I do not understand why there is only one code thrown only for bank 2, when the imbalance is on both banks.

Now I am trying to figure out how to check for vacuum leaks

 

[jons901]

Yes, I am suspecting a vacuum leak too. As both 1st sensors stay locked at 0.1V -> make me think engine runs lean. No matter the rpm.
And it seems they do not enter the closed loop, gets locked lean.
Since it happens on both banks, I do not understand why there is only one code thrown only for bank 2, when the imbalance is on both banks.

Now I am trying to figure out how to check for vacuum leaks

My P0430 popped up a couple weeks ago as well. Incidentally 2 days after my wife's car popped a P0446 (evap system issue). Apparently neither of our cars are excited about the environment right now, but I digress.

I am following the diag procedure from alldatadiy.com:

1. Do you have the code? == > Yes
2. Are there other codes? ==> No (they assume the O2 sensors are good unless another code is found)
3. Check the O2 sensors wiring harness. All OK? ==> Yes
4. Check the fuel pressure. Within spec? ==> ?
5. Check for exhaust leaks. Any found? ==> ?
6. Carry out the Catalyst Monitor Drive Cycle ==>?

I am thinking I may have a vacuum leak as well. I changed the spark plugs a couple months ago but did not replace the intake gasket when I had it off, so that is my next check. I will be replacing the gasket this weekend. I am also thinking that as my short term fuel trim on bank 2 is running just a bit lean as seen below.

Remember to adjust your ranges when looking at the O2 sensors as the range is really small if operating properly:

To check for vacuum leaks one thread I saw said spray some carb cleaner is short bursts around the intake plenum to see if the engine speeds up. I have not verified that or tried it but here is a mechanic talking about it so I may try that as well:



So my question that I have not gotten a straight answer to yet is if I have to check the fuel pressure, what PID is that in Forscan? I have not been able to find it. Alldata has me buying a special adapter to be able to hook up a fuel pressure gauge inline on the fuel rail, but since there is a fuel pressure sensor shouldn't the ECU report that value? Anyone know what PID it is?

 

[1991 sploder]

My P0430 popped up a couple weeks ago as well. Incidentally 2 days after my wife's car popped a P0446 (evap system issue). Apparently neither of our cars are excited about the environment right now, but I digress.

I am following the diag procedure from alldatadiy.com:

1. Do you have the code? == > Yes
2. Are there other codes? ==> No (they assume the O2 sensors are good unless another code is found)
3. Check the O2 sensors wiring harness. All OK? ==> Yes
4. Check the fuel pressure. Within spec? ==> ?
5. Check for exhaust leaks. Any found? ==> ?
6. Carry out the Catalyst Monitor Drive Cycle ==>?

I am thinking I may have a vacuum leak as well. I changed the spark plugs a couple months ago but did not replace the intake gasket when I had it off, so that is my next check. I will be replacing the gasket this weekend. I am also thinking that as my short term fuel trim on bank 2 is running just a bit lean as seen below.


View attachment 324433



Remember to adjust your ranges when looking at the O2 sensors as the range is really small if operating properly:
View attachment 324434

To check for vacuum leaks one thread I saw said spray some carb cleaner is short bursts around the intake plenum to see if the engine speeds up. I have not verified that or tried it but here is a mechanic talking about it so I may try that as well:



So my question that I have not gotten a straight answer to yet is if I have to check the fuel pressure, what PID is that in Forscan? I have not been able to find it. Alldata has me buying a special adapter to be able to hook up a fuel pressure gauge inline on the fuel rail, but since there is a fuel pressure sensor shouldn't the ECU report that value? Anyone know what PID it is?

Ecu should report fuel pressure but sometimes the scanner software isn't comparable with every sensor in the ecu.... Those fuel trims look perfect... Have you tried any fuel system cleaner lately? Uggg garanteed to pass ECT I hate these products.... Have I seen the 02 sensor plug on Amazon with the catylist for downstream 02's? Btw all I'm seeing from the data is a bad cat towards the end of the data? Well at my local exhaust shop there's a big sign that says if your catylitic converter goes out you have other problems....was this data all at idle? At a point in the data ur losing oxygen in the exhaust...

 

[jons901]

Ecu should report fuel pressure but sometimes the scanner software isn't comparable with every sensor in the ecu.... Those fuel trims look perfect... Have you tried any fuel system cleaner lately? Uggg garanteed to pass ECT I hate these products.... Have I seen the 02 sensor plug on Amazon with the catylist for downstream 02's? Btw all I'm seeing from the data is a bad cat towards the end of the data? Well at my local exhaust shop there's a big sign that says if your catylitic converter goes out you have other problems....was this data all at idle? At a point in the data ur losing oxygen in the exhaust...

Yes, this data is at idle after pulling into the garage following a 20ish minute trip around town. I do need to capture at higher RPM's. Right now the light is not on, but it has been a couple times over the last weeks.

I have not run a fuel cleaner since I have owned the vehicle (3 years, 60,000 miles) but I am looking at the seafoam line.

Right, I have seen information from videos, posts, and manufacturers saying cats don't go bad on their own, they get destroyed by other engine problems. So I'm not going to replace it until I have a cause of the failure. If I get a chance this weekend I will also try the shopvac soap bubble test to check for exhaust leaks.