Drive DTCP0420 – Catalytic converter isn't working as well as it should (bank 1)
Catalyst system efficiency below threshold (Bank 1)
Emissions · generic OBD-II code
You can drive it, but take it easy and get it looked at soon – waiting usually makes the repair bigger.
Check this first
Fix any misfire, lean or rich code first – those kill converters, and a new one will die too.
Failing emissions on this code is common. Get the cheap causes ruled out before buying a converter.
What usually fixes it
In the order a good shop checks them. Typical total: $103–$2,206 at $130 an hour.
Downstream oxygen sensor
A lazy rear sensor reports a bad converter when the converter is fine.
Exhaust leak
A leak near the sensors upsets the readings.
Catalytic converter
After a misfire or rich running the converter really is worn out.
What the vehicle can tell you itself
A stored code is a headline, not the story. The vehicle also holds the conditions when it happened, how close the part is to the limit it fails at, what the fuel trims are doing, and whether the fault is still happening right now. Drive DTC reads all of it with a USB adapter and a Windows PC – and it can't change a single setting on the vehicle.
See what your vehicle says about P0420
Codes in plain English, what usually causes them, what the repair costs, and whether it's safe to drive.