Auxiliary Emissions ControlOBD2 Codes

P0430 – Meaning, Causes, Symptoms, & Fixes

Reading Time: 3 minutes

Code P0430 Definition

Catalyst system efficiency below threshold (Bank 2).

P0430 catalyst system efficiency below threshold bank 2

What Does P0430 Mean?

The function of the catalytic converter is to break down harmful pollutants that are created by your vehicle during the combustion cycle and convert them into less harmful gases. Code P0430 indicates that the catalytic converter is not functioning efficiently, therefore increasing the output of harmful pollutants by the vehicle.

What Are the Symptoms of Code P0430?

  • Check Engine Light is on
  • Lack of power from the engine
  • Decreased fuel economy
  • Rotten egg or a sulfur smell

What Is the Cause of Code P0430?

  • Faulty oxygen sensor
  • Faulty air-fuel sensor
  • Worn or internally failing catalytic converter (Most Common)
  • A leak in the exhaust system
  • Misfire (the root cause of converter failure)
  • Rich or Lean air-fuel ratio (the root cause of converter failure)
  • Leaded Gasoline (the root cause of converter failure)

What Is the Severity of Code P0430? – Moderate 


While P0430 does not pose a danger to the driver, it can cause driveability concerns such as a lack of power or poor acceleration if left unrepaired. It can also cause severe damage to other components of your vehicle if not addressed in a timely manner. It is recommended that you address P0430 as soon as possible to keep the cost of the repair to a minimum.

Code P0430 Common Diagnosis Mistakes

Often times this code is thought to be a faulty O2 sensor or A/F Sensor; while this is a possibility, the most common problem is a faulty catalytic converter. Do not overlook other codes that are paired along with P0420. Codes like P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, and P0308 are misfire codes, and these codes require misfire diagnosis. If the catalytic converter is replaced without repairing the misfire, the new catalytic converter will go bad again. Also, make sure you don’t have codes P0174, P0171, P0172, or P0175 which can mean the engine is running rich or lean, which can burn out your catalytic converter. If these codes or any other codes are present, they should be addressed first.

Tools Needed to Diagnose Code P0430 

How to Diagnose Code P0430

Difficulty of Diagnosis: 5 out of 5

  1. Scan your vehicle to verify P0430 is the only code present. If other codes are present, they must be addressed first.
  2. Examine the exhaust system for damage and leaks. Pay close attention to the exhaust manifold, gaskets, and exhaust pipes pre-catalytic converter. If any leaks are found, repair the leak, clear the code, and complete several drive cycles to verify that was the fix.
  3. With the car running and at normal operating temperature, use the digital multimeter to check the voltage reading of the downstream O2 sensor. The downstream O2 sensor produces a relatively steady voltage reading of approximately 0.45V if the catalytic converter is functioning properly. If the voltage of the downstream O2 sensor is constantly jumping between 0.1V and 0.9V, the catalyst is worn and the catalytic converter needs to be replaced.

Estimated Cost of Repair

For error code P0430, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair.

  • Air fuel sensor or oxygen sensor: $200-$300
  • Catalytic converter: $400-$2400
  • A leak in exhaust: $100-$200 (if welded to repair)

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  1. Found out that my exhaust manifold gasket on the front passenger side was bad

  2. I’ll let yoiu. know. haveing a great corvette shop work oin it, in Las Vegas.

  3. I’m getting code PO174 pretty much all the time. Sometimes I get codes PO430 and PO174 together. Sometimes I get PO174 by itself, sometimes PO430 by itself. My car is not displaying any of the PO430 symptoms.

    1. i just replaced my mass air flow meter and had never gotten the po430 code so all the others have been cleared and after around 200 miles of driving this po430 came up. a friend of mine owns a repair shop and he told me to change the mass air flow meter he was right on. now i have a new money pit battle it’s become process of elimination which is expensive.

      1. Fuel injector stuck open or it lost the orfice plate. P0430 is bank 2 meaning side without #1 cylinder.

      2. I have a 2018 dodge journey gt 2 wheel drive v6. I had gotten a p0430 code bought a new catalytic converter for bank 2 catalyst problem. My question to you is which side is bank 2 on my dodge if so please provide a image.

  4. It says to check the voltage of my downstream O2 sensor. How do I do this?

    1. Hi Terry,

      You will need an multimeter in order to check the voltage of your downstream O2 sensor.

      The FIXD Team

      1. I had a car tuned up and then the next day the P0420 and P0430 codes came on. Coincidence?

        1. I just had a tune up on my 2013 ford edge and next day engine light came on and P0430 code registered on my fixd. Is it coincidence?

      2. Well Duhh that’s obvious. Where do I measure the voltage? Is it inside the exhaust?

        1. Just use an OBD2 scanner with live data

          1. FIXD has live data!

  5. what about if the downstream O2 sensor produces a relatively steady voltage reading of approximately 0.75V. my vehicle is a Lincoln MKX 2008

    1. Hi Roberto,

      The consistency of your voltage reading means that your downstream O2 sensor is operating correctly.

      The FIXD Team

      1. Does this mean the cat is bad?

        1. My Downstream O2 Sensor voltage reading is a consistent .75 when running/idle (according to FIXD)…..I’d have the same question, does this mean the cat is bad? ‘07 Jeep Wrangler JK

          1. No it means it’s good with a constant read on voltage. If it was jumping way low to high then it’s bad

  6. I had a tune up done on a 2003 Toyota RAV 4 and now the P0420 and P0430 codes came on. Any ideas?

  7. I just replaced both 02 sensors
    Bank 1 sensor 2 and bank 2 sensor 2 last week and my check engine light came on today with the code p0430

  8. I tried pushing the Clear Check Light about 5-8 times and the light stayed on. Turned engine off and back on and the light is still on. I took it to the Dealer about 6 months ago when the light came on. They said they would replace the most expensive part first about $1500, I said I would wait. Then cleared the light until now.

  9. If the downstream O2 sensor on Bank 2 is jumping between 0.1V and 0.9V, how do I know that the catalytic converter needs to be replaced and it’s not just a bad O2 Sensor?

  10. I just replaced my catalytic converter and all O2 sensors less than 5 months ago and this code was thrown while cruising down the highway. Could this be caused by something I had replaced improperly?

    2012 Ford F150 Ecoboost

    1. Hey did you figure out your problem with your f150? I have the same problem on my 2011 f150.

      1. I have the same on my 2013 5.0. Started with a bad o2 an bank 1 that took out the bank 1 cat. Replaced 4 o2 sensors and both cats(went aftermarket Walker). Been plagued with this p0430 ever since. Finally fixed it. Found a small leak at the manifold gaskets. I’d never had thought that small of a leak could do this. I actually had to use soapy water to find the leak because 2 exhaust shops told me it wasnt leaking. But sure enough they were and the headache is finally over.

        1. Hi can you please tell me how I can do the same to check for any leaks before I replace my Cats.

          1. I have 07 Chrysler Aspen throwing a p0430 code. It started out with p0420 but I used Cataclean and now I got the 430 code. Ugh…help please ?.

        2. Did you use a spray bottle for the soapy water? What did u use?

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  12. I’m getting the P0430 code with increasing frequent y. However I’m not getting any lost of power, rotten egg smells or reduction in fuel economy. I’m thinking the O2 sensor is going out. Thoughts?

  13. I replaced my O2 sensor (Bank 2 sensor 2) for this code as it was $20. I’m still intermittently getting just the P0430 code (maybe once every 20 minutes). I clear the code and watch the O2 sensor live on my ODB scanner/bluetooth app – the Bank 1 sensor 2 stays around .55 going up and down slightly as I drive. The Bank 2 sensor 2 also does this but every once in a while (maybe 5 minutes) it troughs and dips down to close to zero and then comes back up to normal range. It’s not a cliff to zero but more of a “U” shape. Based on the reading above would you think I have another faulty O2 sensor or possibly an exhaust leak? Vacuum leak? 07 Yukon 193K 5.3L 4×4

    1. Mai car chekinzin p0430

  14. On the code for Bank 2, which side is Bank 2 on a 2007 Jeep Wrangler 3.8 V-6? Jeep has over 157,000 miles, in fact I just recently bought it. Is this code P0430 common on these Jeeps? Why am I not getting any other codes for BANK 1, but just BANK 2?

    1. Bank 2 on a V engine is whichever side cylinder 2 is in. Bank one is the side with cylinder 1. At least in the 6-7 vehicles I work on. General rule. Ur firing order under hood will tell you which cylinder is 1 &2

      1. Drivers side rear sensor

  15. I keep on getting this code Po430 it goes on it goes off sometimes I stay off 4 to 3 weeks then I’ll come back on if I put the meter on it when it’s off it says everything’s okay sometimes it stays on for a couple of days then goes off what could this mean

    1. If the timing belts were replaced on recall, could the misfires caused by bad belts cause the catalytic converter to fail??

  16. When the engine light comes on I fill up with high grade gasoline and that takes care of it.

    1. Not me…. I pour straight bourbon whiskey down it’s throat

  17. What reading do you get if the O2 Sensor is bad and not the converter because I have 2 of them. 1 b4 the converter and 1 after the converter? 2009 Cadillac CTX

    PS I would assume you have to peel back the skin in order to test the lead going into the sensor?


  18. I just replaced all four sensors and catalytic converters 3 days ago and still get this code. Any ideas why?

    1. Check for exhaust leaks even tiny ones. Try soapy water on a cold start and rev it up. If you see bubbles chances are exhaust leak is the culprit. I had 2 exhaust shops tell me there was no leak but sure enough there was one so small I couldn’t tell until I used soapy water

  19. I have 2004 Toyota canary. Keep getting this code. P0430

    My fix what I found was. Over time I was loosing coolant slowly. When I change sparkplugs. I had to remove intake manifold to change back plugs. I found intake had crack in it that looks like it was crack for while.
    I replace intake. Had no issue for 6 months now.
    Point I’m getting at. Check for vacuum leaks

  20. I have the same on my 2013 5.0. Started with a bad o2 an bank 1 that took out the bank 1 cat. Replaced 4 o2 sensors and both cats(went aftermarket Walker). Been plagued with this p0430 ever since. Finally fixed it. Found a small leak at the manifold gaskets. I’d never had thought that small of a leak could do this. I actually had to use soapy water to find the leak because 2 exhaust shops told me it wasnt leaking. But sure enough they were and the headache is finally over.

  21. I have a 2012 F150 Ecoboost and the check engine light turns on with the P0403 code only to turn off a few days later for anywhere from 2-4 weeks. The code is p0430 but why would the check engine light turn on and then off?

  22. 07 santafe just got it?

  23. I replaced the cats on my 2009 GMC Acadia in February of this year because my check engine light started flashing. Prior to that my husband had replaced 2 of the 3 O2 sensors it has, not knowing it has 3. We’ve sense replaced the 3rd one after finding out it has 3. Today we replaced the upstream sensor again and I’m still getting the P0420 and P0430 codes. Surely my cats have not gone bad since February?? PLEASE help!

  24. my 2004 4runner has gotten the P0430 code with a rotten egg smell. After clearing the code, it doesnt pop up till around 1000km later. but still get the smell while reving the engine. I believe this to be a bad cat due to the smell but havent yet confirmed it nor took it into a shop

  25. How do you know if it’s the converter that’s bad or if it’s just a bad O2 sensor or bad gasket? Of course, a mechanic is going to go for the most expensive fix ie converter.

  26. Not sure this forum has any value. I do not see any answers to the problems posted here. I may just be technically challenged as I am very old. If I’m doing something wrong please help me get it right.

  27. 2004 Dodge Ram 5.7L with new engine, at 70 mile mark engine light comes on scanner shows P0430 bank 2, went to live data 02B2S2 reads 0.055v.
    , does not change/fluctuate or cycle just sits there at 0.055 volts, 02 sensors on bank 2 replaced recently, original converters with 90k on them, went for a 12 mile ride then checked temp on bank 2 cat with inferred gun inlet 370 degrees outlet 410 degrees, 40 degree diff. Any ideas?

  28. I had the same from a large O company????

  29. I had p0430 on a 2016 pilot. Took it to the dealer just this week. They said they replaced the fuel injectors on warranty and at no cost to me (saved 1600-1800).

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