Skip the auto shop - Our mechanics make house calls

Q: Scan vehicle Code P0430 Cataylic system efficiency below threshold bank 2

asked by on

Hi,

Month ago had a misfire on my vehicle Lincoln Town Car so I use a scanner and had a code which said cyclinder 2 misfire so I took it to my Mechainc and he replace just 1 coil and 1 spark plug the rest was not replace my Mechainc said you don't need to replace them til it fails. Car ran nicely after a month now my car as another problem check engine light on and blinking as well my car is running rough, jerking, and shaking when I acceralte. So I went and bought a bottle of Fuel & Exhaust system cleaner which is suppose to clean the Cataylic and 02 sensor to give a shot to see but no luck but it did help a little bit so I ran the scanner and it give me a code which say PO430 Cataylic system efficiency below threshold bank 2. Can you please tell me what is the cause of this problem is it the 02 sensor or Cataylic convertor or something else as I have no clue?

My car has 214500 miles.
My car has an automatic transmission.

A: The code is meant to indicate your catalyti...

The code is meant to indicate your catalytic converter is not performing up to par with the EPA (environmental protection agency) standards. Your car uses the oxygen sensors to monitor the catalytic converter (cat) efficiency. There is an O2 sensor before and after the cat. If the catalytic is working effectively, the O2 sensor after the catalyst will show much less HC's (hydrocarbons) that at the front of the cat. If the cat is not performing as it should, the rear O2 will see close to the same amount of HC's after the catalytic converter.

Most of the time this code requires the replacement of the catalytic converter. There are times when one or both of the O2 sensors that monitor the cat are bad. This can be determined by monitoring scan tool data for a reaction from the O2 when you snap the throttle. In addition, you can use an exhaust gas analyzer monitor the tail pipe emissions from a cold start up. The cat takes sometime to begin working on a cold start, so there should be a significant difference in tailpipe emissions once the cat warms up. Gas analyzers are very expensive, so it is unlikely most people will have access to one. If you need a definitive diagnosis, a certified professional from YourMechanic can come to your car's location to pinpoint the cause of the code and proceed with repair.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: The Check Engine light is on. I know the vehicle needs a new catalytic converter.

If someone has already diagnosed that the catalytic converter is faulty on your vehicle and you know they are correct, that is the cause of your check engine light. Your oxygen sensors pick up more fuel in the exhaust when...

Q: Clutch sticking to floor

It does sound like you have a hydraulic problem. First, I would check for external leaks. If none are found, the problem could be air in the system. This could be the result of not bleeding the system properly after...

Q: Dead short in the electrical system.

I would ask for help from one of the mechanics at YourMechanic. They will have one of their mechanics come to you with the proper test equipment and knowledge to diagnose a fix the short in your electrical system.

Related articles

How to Renew Your Car Registration in Oklahoma(DELETED)
Having your car registered with the Oklahoma Tax Commission is an important part of driving legally in this state. You will need to do this within 30 days of moving to Oklahoma...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.