P0430 – Meaning, Causes, Symptoms, & Fixes

Code P0430 Definition

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 during the combustion cycle and convert them into harmless gases. Code P0430 indicates that the catalytic converter is not functioning efficiently, therefore increasing the output of harmful pollutants by the vehicle.

P0430 Symptoms

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

P0430 Causes

  • Faulty oxygen sensor
  • Worn and internally failing catalytic converter
  • Leak in exhaust system

Code P0430 Severity – Moderate    

While P0430 does not pose a danger to the driver and may not produce any symptoms with issues related to drivability, it can cause severe damage to other components 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

Do not overlook other codes that are paired along with P0430. Codes P0300, P0301, P0302, P0303, P0304, P0305, P0306, P0307, P0308, P0174, and P0171 can give false data readings that create conditions which trigger code P0430. If any other codes are present, they should be addressed first.

P0430 Diagnosis

Tools Needed to Diagnose:
  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.
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Comments 24

Michael Hutchins

June 5, 2018

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


June 5, 2018

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

Mike Weber

June 5, 2018

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.

Terry Barker

June 27, 2018

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

FIXD Marketing

July 9, 2018

Hi Terry,

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

The FIXD Team


August 5, 2018

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


November 25, 2018

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?

Adam Mizban

October 2, 2018

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

roberto Gutierrez

July 9, 2018

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

FIXD Marketing

July 9, 2018

Hi Roberto,

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

The FIXD Team


November 12, 2018

Does this mean the cat is bad?


August 5, 2018

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


August 13, 2018

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

Jack Boal

August 17, 2018

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.


August 20, 2018

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?


August 23, 2018

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


September 4, 2018

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David Harrison

September 7, 2018

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?

Ben Van Heirseele

September 8, 2018

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


November 20, 2018

Mai car chekinzin p0430

Richard Shutter

September 24, 2018

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?


September 24, 2018

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


October 10, 2018

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

Tommie Taylor

October 21, 2018

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?