P0420 on Kia vehicles
96 owner complaints filed with NHTSA about Kia vehicles mention P0420 (Catalyst System Efficiency Below Threshold Bank 1) - across 6 models. Below is where it shows up, by model and year.
Can you drive with it? Yes - the car remains driveable. Fix it before emissions testing: this code is an automatic inspection failure in most states.
Symptoms, likely causes in order and realistic repair costs are on the main P0420 page - they do not differ much by brand. This page shows what is specific to Kia: which models and years actually report it.
Kia models reporting P0420
The number next to each year is how many NHTSA complaints for that car mention P0420. Owners rarely quote trouble codes when complaining, so real occurrence is many times higher - use these numbers to compare years, not as totals.
What Kia owners report
“Multiple times with 6 months my check engine light comes on but no code is detected. However, when tested it tells me to look out for code P0420. The issues I have encountered: - High RPM of 2,000 when vehicle is started - Check engine light with no code. Light comes and goes on it own - Car jolts and vibrates high while idling - Car eats oil like no tomorrow. Having to do an oil change every 3,000 miles”2014 Kia Soul · May 2026
“My car burns oil very fast. I am putting in more than 5 quarts of oil in between oil changes. I have replaced the flex pipe, the catalytic converter two times, and both the upstream and downstream oxygen sensors. The catalytic converter now needs to be replaced again after only 7 months after being installed. The car keeps getting P0420 codes. I found out this last converter was bad while on the highway going 70 mph up a hill. The speed suddenly decreased all the way down to 50 mph which put me in great danger of getting hit from behind at high speeds. It would not go any faster..”2014 Kia Soul · Apr 2026
“I have a code of P0420 show up on a vehicle diagnostic test. This is directly related to recall SA363 ECU LOGIC . The engine light kept coming on. I was driving on the highway and the car stalled and then stopped as I was coming off the exit.”2019 Kia Soul · Mar 2026
“Engine burning excessive oil over a quart in 1000 miles. Catalytic converter code P0420 because of the excessive oil burning. Oil was always changed within the specified dealer milage range.”2020 Kia Forte · Mar 2026
P0420 on other makes
Makes with enough NHTSA reports of P0420 for their own page.
Counts are NHTSA owner complaints whose text mentions P0420 - owner-reported and unverified. Always confirm with a diagnosis of your specific vehicle.