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

asked by on October 14, 2016

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.

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?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Car has shut off because of overheating.. What to do

Overheating can be caused by a number of things such as low coolant levels, a faulty thermostat, a clogged radiator or a failing coolant fan switch. As you may know the coolant fan switch helps to maintain the proper coolant...

Car oil leak

Hello. The oil can leak from any number of places on this engine. The most common places that this engine leaks oil is from the valve cover gaskets, and from the rear main seal. If it is dripping while the...

Sensor messed up

Hello. There should be a Check Engine warning light on the dash display. It could also be a loose connection if you recently had exhaust work done. If you have any failure in the catalyst sensors or wiring, it should...

Related articles

B2106 OBD-II Trouble Code: Throttle Position Input Out of Range High
B2106 trouble code means there's a range issue with the throttle position input in a 4WD system, caused by a damaged circuit in the 4WD system.
P0209 OBD-II Trouble Code: Injector Circuit Malfunction - Cylinder 9
P0209 P0209 code definition Injector Circuit Malfunction - Cylinder 9 What the P0209 code means The meaning of the P0209 code is that the fuel injector circuit was found to have out of range voltage or resistance. This out...
P0229 OBD-II Trouble Code: Throttle/Pedal Position Sensor/Switch C Circuit Intermittent
P0229 P0229 code definition Throttle/Pedal Position Sensor/Switch C Circuit Intermittent What the P0229 code means P0229 is an OBD-II generic code indicating the throttle/pedal position sensor/switch C circuit has an intermittent input problem causing the sensor input to the engine...