P0420 on Acura vehicles The catalytic converter on bank 1 is not cleaning up the exhaust as well as it should
P0420 is named on 5 Acura model years (2016–2019): 22 manufacturer filings and 1 owner report in NHTSA’s files, across TLX, MDX.
Which Acura model years name P0420
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2017 Acura TLX | Engine | 6 | — |
| 2016 Acura TLX | Engine | 6 | — |
| 2019 Acura TLX | Engine | 5 | — |
| 2018 Acura TLX | Engine | 5 | — |
| 2016 Acura MDX | 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.
Acura filings that name P0420
Source: NHTSA manufacturer communicationsBulletins and campaigns Acura 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.
- BPaS10172018906 Service bulletin2018-10-17 · Electrical System
- Dealer message - American Honda Motor Co., Inc. (AHM) is investigating certain 2015-2019 TLXs with a client complaint of the Malfunction Indicator Lamp (MIL) on with DTC P0420 (Rear Bank Catalyst System Efficiency Below Threshold [Bank 2]) and/or P0430 (Front Bank Catalyst Sytem Efficiency Below Threshold [Bank 2]) stored. To fully understand the cause of this condition, AHM would like to inspect
- BPaS11052018904 Service bulletin2018-11-05 · Engine And Engine Cooling
- Dealer message - American Honda Motor Co., Inc. (AHM) is investigating certain 2015-2019 TLXs with a client complaint of the Malfunction Indicator Lamp (MIL) on with DTC P0420 (Rear Bank Catalyst System Efficiency Below Threshold [Bank 2]) and/or P0430 (Front Bank Catalyst Sytem Efficiency Below Threshold [Bank 2]) stored. To fully understand the cause of this condition, AHM would like to inspect
- BPaS11262018905 Service bulletin2018-11-26 · Engine And Engine Cooling
- Dealer message - American Honda Motor Co., Inc. (AHM) is investigating certain 2015-2019 TLXs with a client complaint of the Malfunction Indicator Lamp (MIL) on with DTC P0420 (Rear Bank Catalyst System Efficiency Below Threshold [Bank 2]) and/or P0430 (Front Bank Catalyst Sytem Efficiency Below Threshold [Bank 2]) stored. To fully understand the cause of this condition, AHM would like to inspect
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 Acura and its owners have filed about it; the code’s page across every make has the whole file.
Common questions
Source: NHTSA files and the OBD-II standardIs P0420 a known problem on Acura vehicles?
It is a documented one: NHTSA's files hold 22 manufacturer filings and 1 owner report naming P0420 on 5 Acura model years (2016–2019). 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 Acura models does P0420 appear on most?
2017 TLX (6 documents), 2016 TLX (6 documents), 2019 TLX (5 documents).
Does P0420 on a Acura 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.