P0420 on Cadillac vehicles The catalytic converter on bank 1 is not cleaning up the exhaust as well as it should
P0420 is named on 5 Cadillac model years (2016–2019): 5 manufacturer filings and 0 owner reports in NHTSA’s files, across CTS, XTS.
Which Cadillac model years name P0420
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2019 Cadillac CTS | Engine | 1 | — |
| 2018 Cadillac CTS | Engine | 1 | — |
| 2018 Cadillac XTS | Engine | 1 | — |
| 2017 Cadillac XTS | Engine | 1 | — |
| 2016 Cadillac XTS | 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.
Cadillac filings that name P0420
Source: NHTSA manufacturer communicationsBulletins and campaigns Cadillac 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.
- 16NA111 Service bulletin2019-03-20 · Engine
- This informational bulletin provides diagnostic/inspection information for the air box and air filter seal to correct a MIL and DTCs P0420 and P0430 setting.
- 17-NA-321 Service bulletin2017-10-01 · Engine And Engine Cooling — Exhaust System — Emission Control — Catalytic Convertor
- Exhaust Smell and/or Leak with Possible Malfunction Indicator Lamp Illuminated Condition Some customers may comment on an exhaust smell and/or leak with possible malfunction indicator lamp illuminated. During diagnosis, a technician may find DTC P0430 and/or P0420. Cause This may be due to a crack around the catalytic mounting flange. Correction Replace converter assembly with new servi
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 Cadillac 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 Cadillac vehicles?
It is a documented one: NHTSA's files hold 5 manufacturer filings and 0 owner reports naming P0420 on 5 Cadillac 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 Cadillac models does P0420 appear on most?
2019 CTS (1 document), 2018 CTS (1 document), 2018 XTS (1 document).
Does P0420 on a Cadillac 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.