Q: The engine light is on and the code is P0420 - Catalyst System Efficiency Below Threshold Bank . What part do I need to fix it?

asked by on

The engine light is on and we just want to know what the part needed to fix this issue. the code is P0420 - Catalyst System Efficiency Below Threshold Bank . However I dont know if its downstream or upstream.

My car has 130267 miles.
My car has an automatic transmission.

While a number of things like a faulty oxygen sensor or exhaust leak can cause fault code P0420 to be set, the most common fault is the catalytic converter itself. However, as a replacement can be very expensive, your best be is to have a certified technician properly diagnose why code P0420 was set in the system.

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
  1. Home
  2. Questions
  3. The engine light is on and the code is P0420 - Catalyst System Efficiency Below Threshold Bank . What part do I need to fix it?

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

Q: Q: Car not starting when Check Engine light is on

The most common problems for this car not starting is the distributor assembly components like the ignition module, coil, cap, rotor, distributor seal leaking oil into the distributor components. The best recommendation is to replace the distributor as an assembly....

Q: tailgate open warning light comes on when closed

As the latches wear with use, the switch that turns on and off the light and door ajar gets worn contacts and the latches do not close the switch contact all the way. This is why you can push in...

Q: Chevy 5.3l - Lost oil pressure, why?

Hello - since you didn't appear to be leaking oil in a significant way (busted oil line, hole in the pan), I suspect that the oil pressure relief valve may have been stuck in the "relief" position. Some of the...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.