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Home›Trouble codes›P0420› Kia
Diagnostic trouble code · Kia

P0420 on Kia vehicles The catalytic converter on bank 1 is not cleaning up the exhaust as well as it should

P0420 is named on 15 Kia model years (2016–2023): 4 manufacturer filings and 39 owner reports in NHTSA’s files, across Soul, Forte, Niro, Sportage, Optima and 1 more.

Powertrain 15 model years 4 manufacturer filings 39 owner reports

Which Kia model years name P0420

Source: NHTSA manufacturer communications and complaints
Model yearFiled underBulletinsOwner reports
2016 Kia SoulEngine219
2017 Kia SoulEngine—3
2022 Kia NiroEngine—2
2021 Kia SoulEngine—2
2020 Kia ForteFuel/Propulsion System—2
2020 Kia SoulUnspecified—2
2019 Kia SoulEngine—2
2016 Kia SportageEngine2—
2023 Kia ForteElectrical System—1
2021 Kia SorentoPower Train—1
2018 Kia SoulEngine—1
2018 Kia SportageEngine—1
2017 Kia SportageEngine—1
2016 Kia OptimaEngine—1
2016 Kia SorentoEngine—1

A model year is listed because the code is named in its own record — a bulletin filed against it, or an owner’s complaint about it — not because every one of these vehicles sets it. Counts are documents in NHTSA’s files, not failure rates.

Engine 31 Power Train 3 Unspecified 3 Fuel/Propulsion System 2
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What Kia owners said

Source: NHTSA complaint database

Owners’ own words, scrubbed of anything identifying. Unverified reports filed with NHTSA — what was said, not a finding that it was true.

After the engine replacement, the vehicle developed additional drivability and warning-light concerns, including P0420 and communication/CAN faults
2020 Kia Soul Sep 4, 2026 NHTSA owner report

Kia filings that name P0420

Source: NHTSA manufacturer communications

Bulletins and campaigns Kia filed with NHTSA whose summary names P0420. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

What P0420 means

Source: SAE J2012 / OBD-II

The catalytic converter on bank 1 is not cleaning up the exhaust as well as it should.

A stored code names the test that failed, never the part that caused it. The record above is what Kia and its owners have filed about it; the code’s page across every make has the whole file.

From here
Get a model's new bulletins by email See what owners reported Look up a bulletin by its number Watch a VIN for new recalls

Common questions

Source: NHTSA files and the OBD-II standard

Is P0420 a known problem on Kia vehicles?

It is a documented one: NHTSA's files hold 4 manufacturer filings and 39 owner reports naming P0420 on 15 Kia model years (2016–2023). Whether it is a problem on one particular car is a diagnosis, not a count — but a bulletin that names the code on your model year is the place to start.

Which Kia models does P0420 appear on most?

2016 Soul (21 documents), 2017 Soul (3 documents), 2020 Forte (2 documents).

Does P0420 on a Kia mean it is recalled?

No. Recalls are filed by campaign and matched by VIN; no recall is triggered by a scan tool. Check the VIN at nhtsa.gov/recalls, or open the model year's page here for the campaigns filed against it.

Where to go next

pages beside this code
Filed alongside P0430 Another code that appears in the same filings and owner reports as P0420.Filed alongside P0087 Another code that appears in the same filings and owner reports as P0420.Vehicle 2016 Kia Soul The model year P0420 is filed against most often.The data Trouble codes by API GET /v1/dtc joins every code to bulletins and owner reports — free tier, no card.