Diagnostic trouble code · Honda
P0420 on Honda vehicles The catalytic converter on bank 1 is not cleaning up the exhaust as well as it should
P0420 is named on 29 Honda model years (2016–2025): 80 manufacturer filings and 21 owner reports in NHTSA’s files, across Fit, Pilot, Odyssey, Ridgeline, Accord and 4 more.
Powertrain 29 model years 80 manufacturer filings 21 owner reports
Which Honda model years name P0420
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2017 Honda Fit | Engine | 14 | 2 |
| 2018 Honda Fit | Engine | 8 | 2 |
| 2017 Honda Pilot | Engine | 4 | 4 |
| 2019 Honda Odyssey | Engine | 2 | 5 |
| 2016 Honda Pilot | Engine | 2 | 4 |
| 2025 Honda Pilot | Engine | 5 | — |
| 2018 Honda Odyssey | Engine | 4 | 1 |
| 2017 Honda Ridgeline | Engine | 4 | — |
| 2019 Honda Pilot | Equipment | 2 | 1 |
| 2024 Honda Accord | Engine | 2 | — |
| 2024 Honda CR-V | Engine | 2 | — |
| 2024 Honda Civic | Engine | 2 | — |
| 2023 Honda Accord | Engine | 2 | — |
| 2023 Honda CR-V | Engine | 2 | — |
| 2023 Honda Civic | Engine | 2 | — |
| 2022 Honda Accord | Engine | 2 | — |
| 2022 Honda Civic | Engine | 2 | — |
| 2021 Honda Accord | Engine | 2 | — |
| 2021 Honda Civic | Engine | 2 | — |
| 2020 Honda Accord | Engine | 2 | — |
| 2019 Honda Accord | Engine | 2 | — |
| 2019 Honda Ridgeline | Electrical System | 2 | — |
| 2018 Honda Accord | Engine | 2 | — |
| 2018 Honda Pilot | Power Train | 2 | — |
| 2018 Honda Ridgeline | Engine | 2 | — |
| 2016 Honda Fit | Fuel/Propulsion System | 2 | — |
| 2018 Honda CR-V | Fuel/Propulsion System | — | 1 |
| 2016 Honda CR-Z | Engine | 1 | — |
| 2016 Honda HR-V | Engine | — | 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 78 Fuel/Propulsion System 10 Equipment 4 Power Train 3
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What Honda owners said
Source: NHTSA complaint databaseOwners’ own words, scrubbed of anything identifying. Unverified reports filed with NHTSA — what was said, not a finding that it was true.
The contact associated the failure with Technical Service Bulletin: 21-010 (Warranty Extension: MIL Comes On with DTC P0420, P0430, P030x, and P219A/B (Without Software Update); however, the vehicle was not covered under the TSB
Honda filings that name P0420
Source: NHTSA manufacturer communicationsBulletins and campaigns Honda 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.
- ATI&11282023910 Service bulletin2023-11-28 · Engine And Engine Cooling
- Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2017-2018 Fits with customer complaint of Check Engine Light (CEL) on with DTC P0420 (Catalyst System Efficiency Below Threshold) stored. To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to your attempting a repair of any kind.
- ATI&01022024909 Service bulletin2024-01-02 · Engine And Engine Cooling — Exhaust System — Emission Control — Catalytic Convertor
- Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2017-2018 Fits with customer complaint of Check Engine Light (CEL) on with DTC P0420 (Catalyst System Efficiency Below Threshold) stored. To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to your attempting a repair of any kind.
- ATI&01172024905 Service bulletin2024-01-17 · Engine And Engine Cooling
- Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2017-2018 Fits with customer complaint of Check Engine Light (CEL) on with DTC P0420 (Catalyst System Efficiency Below Threshold) stored. To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle prior to your attempting a repair of any kind.
- A20-100 Service bulletin2021-02-11 · Power Train — Automatic Transmission — Control Module (Tcm/Pcm/Tecm)
- "Service Bulletin - The PCM software may misinterpret sensor inputs as a deteriorated catalytic converter. Additionally, debris from the high pressure pump or the fuel injector machining process can cause internal wear or clogging inside one or more injectors. One or more of the following DTCs may be stored: - P0420 (rear bank catalyst system efficiency below threshold [bank 1]) - P0430 (front b
- A21-010 Service bulletin2021-02-11 · Engine And Engine Cooling
- "Service Bulletin - The PCM software may misinterpret sensor inputs as a deteriorated catalytic converter. Additionally, debris from the high pressure pump or the fuel injector machining process can cause internal wear or clogging inside one or more injectors. One or more of the following DTCs may be stored: - P0420 (rear bank catalyst system efficiency below threshold [bank 1]) - P0430 (front b
- ONLN9403292021 Service bulletin2021-03-29 · Equipment
- "Owner Notification Letter - On some 2017-19 Pilot, 2017-19 Ridgeline, and 2018-19 Odyssey models, the malfunction indicator light (MIL) may come on if one or more of the following diagnostic trouble codes (DTCs) are stored: - P0420 (rear bank catalyst system efficiency below threshold [bank 1]) - P0430 (front bank catalyst system efficiency below threshold [bank 2]) - P0300-P0306 (misfire) -
- ONLW8V03292021 Service bulletin2021-03-29 · Equipment
- "Owner Notification Letter - On some 2016-17 Pilot, 2017 Ridgeline, and 2018 Odysey models, the malfunction indicator light (MIL) may come on if one of the following diagnostic trouble codes (DTCs) are stored: - P0420 (rear bank catalyst system efficiency below threshold [bank 1]) - P0430 (front bank catalyst system efficiency below threshold [bank 2]) - P0300-P0306 (misfire) - P219A (air-fuel
- ATI&01142026905 Other2026-01-14 · Engine
- Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2025 Pilots with customer complaint of Check Engine Light (CEL) on with DTC P0420 [Catalyst System Efficiency Below Threshold (Bank 1)] and/or P0430 [Catalyst System Efficiency Below Threshold (Bank 2]] stored. To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle.
- ATI&01302026904 Other2026-01-31 · Engine
- Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2025 Pilots with customer complaint of Check Engine Light (CEL) on with DTC P0420 [Catalyst System Efficiency Below Threshold (Bank 1)] and/or P0430 [Catalyst System Efficiency Below Threshold (Bank 2]] stored. To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle.
- ATI&04132026905 Other2026-04-13 · Engine
- Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2025 Pilots with customer complaint of Check Engine Light (CEL) on with DTC P0420 [Catalyst System Efficiency Below Threshold (Bank 1)] and/or P0430 [Catalyst System Efficiency Below Threshold (Bank 2]] stored. To better understand the cause of this condition, AHM would like to collect specific parts from the vehicle.
- ATI&11052024902 Other2024-11-05 · Engine
- Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2018-2024 Accord 1.5Ls, 2021-2024 Civics 1.5Ls, 2023-2024 CR-Vs 1.5Ls, and 2017 Fits with customer complaint of Check Engine Light (CEL) on with DTC P0420 [Catalyst System Effciency Below Threshold] stored. To better understand the cause of this condition, AHM would like to specific parts from the vehicle prior to you a
- ATI&12022024909 Other2024-12-03 · Engine
- Dealer Message - American Honda Motor Co., Inc. (AHM) is searching for certain 2018-2024 Accord 1.5Ls, 2021-2024 Civics 1.5Ls, 2023-2024 CR-Vs 1.5Ls, and 2017 Fits with customer complaint of Check Engine Light (CEL) on with DTC P0420 [Catalyst System Efficiency Below Threshold] stored. To better understand the cause of this condition, AHM would like to specific parts from the vehicle prior to you
What P0420 means
Source: SAE J2012 / OBD-IIThe 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 Honda and its owners have filed about it; the code’s page across every make has the whole file.
From here
Common questions
Source: NHTSA files and the OBD-II standardIs P0420 a known problem on Honda vehicles?
It is a documented one: NHTSA's files hold 80 manufacturer filings and 21 owner reports naming P0420 on 29 Honda model years (2016–2025). 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 Honda models does P0420 appear on most?
2017 Fit (16 documents), 2018 Fit (10 documents), 2017 Pilot (8 documents).
Does P0420 on a Honda 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.