P0420 on KIA SOUL — Catalyst System Efficiency Below Threshold Bank 1

Q: "What does P0420 mean on a KIA SOUL?"

"P0420 indicates: Catalyst System Efficiency Below Threshold Bank 1. This is a emission controls code. 68 KIA SOUL owners have reported this to NHTSA."

Q: "What are the most common causes of P0420 on KIA SOUL?"

"Based on 68 NHTSA reports, the most commonly cited components are: Engine, Engine And Engine Cooling,Engine, Unknown Or Other,Engine,Fuel/Propulsion System. These percentages are based on the component field in owner complaints."

Q: "Is P0420 a safety concern on KIA SOUL?"

"Of 68 NHTSA reports for P0420 on KIA SOUL, 1 involved a crash and 2 involved a fire. Always consult a qualified mechanic for any diagnostic trouble code."

Q: "What should I do if my KIA SOUL shows P0420?"

"1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare."

What P0420 Means on Your KIA SOUL

P0420 is a diagnostic trouble code indicating: Catalyst System Efficiency Below Threshold Bank 1. This code relates to the emission controls system. The vehicle's computer detected a condition outside normal operating parameters and stored this code.

68 KIA SOUL owners have reported this issue to NHTSA across model years 2012-2021. Most reports come from the 2015, 2016 model years. The most commonly reported component is Engine (50.0% of reports).

Real KIA SOUL Owner Reports

Source: NHTSA Complaints Database

"I bought the car 2 yrs ago come April and it's had nothing but issues. I've had one recall did which was the knock sensor however now the check engine is on and it's smelling like rubber my brakes are wearing like an eraser and my engine just feels sluggish."

— 2012 KIA SOUL owner · VEHICLE SPEED CONTROL,SERVICE BRAKES,ENGINE · Filed 10/26/2025

"So I purchased a 2012 Kia Soul A few months ago and since I got it the car has been having issues with accelerating the car delays to respond and I have had many closed calls specifically when entering a freeway the car losses power and I have to really press on the pedal for the vehicle to respond"

— 2012 KIA SOUL owner · VEHICLE SPEED CONTROL,ENGINE,FUEL/PROPULSION SYSTEM · Filed 04/02/2024

"The contact owns a 2012 Kia Soul. The contact stated while driving 45 MPH, the check engine warning light illuminated."

— 2012 KIA SOUL owner · ENGINE AND ENGINE COOLING,ENGINE · Filed 02/08/2023

"My vehicle's malfunction light came on and it began to lose power off and on going down the turnpike. since then, it sometimes won't start even though it sounds like it is going to. it continues to have these problems intermittently."

— 2012 KIA SOUL owner · ENGINE · Filed 03/27/2021

"7/22/20 - car driven to firestone store #005738, newport, ky to purchase 2 new tires and an engine courtesy check was performed - firestone id #7046930 - no engine lights, no safety warnings, mileage 77,071 miles on car."

— 2012 KIA SOUL owner · ENGINE · Filed 07/22/2020

All reports filed by vehicle owners directly with the U.S. Department of Transportation.

📊 Complaint Trend by Model Year

7

'12

10

'13

11

'14

20

'15

13

'16

3

'17

1

'18

1

'19

1

'20

1

'21

Common Causes on KIA SOUL

Based on NHTSA complaint component analysis for this vehicle.

ENGINE 50%

ENGINE and ENGINE COOLING,ENGINE 4.4%

UNKNOWN or OTHER,ENGINE,FUEL/PROPULSION SYSTEM 4.4%

ENGINE,FUEL/PROPULSION SYSTEM 4.4%

UNKNOWN or OTHER,ENGINE 4.4%

What To Do Next

1
Check for recalls on YOUR VIN
Go to nhtsa.gov/recalls and enter your VIN. If your vehicle is covered, repairs are free.
2
Get a proper diagnosis
A code alone doesn't tell you the exact failed part. A diagnostic at a shop ($50–$150) pinpoints the root cause before you spend money on parts.
3
Compare repair quotes
Get 2–3 quotes. Dealer vs. independent shop prices often differ 30–50% for the same repair.

Frequently Asked Questions

What does P0420 mean on a KIA SOUL? ▾

P0420 indicates: Catalyst System Efficiency Below Threshold Bank 1. This is a emission controls code. 68 KIA SOUL owners have reported this to NHTSA.

What are the most common causes of P0420 on KIA SOUL? ▾

Based on 68 NHTSA reports, the most commonly cited components are: Engine, Engine And Engine Cooling,Engine, Unknown Or Other,Engine,Fuel/Propulsion System. These percentages are based on the component field in owner complaints.

Is P0420 a safety concern on KIA SOUL? ▾

Of 68 NHTSA reports for P0420 on KIA SOUL, 1 involved a crash and 2 involved a fire. Always consult a qualified mechanic for any diagnostic trouble code.

What should I do if my KIA SOUL shows P0420? ▾

1) Check for recalls on your VIN at nhtsa.gov/recalls. 2) Get a professional diagnosis — a code alone doesn't identify the exact failed part. 3) Get 2-3 repair estimates to compare.