C056D on GMC vehicles
C056D is named on 19 GMC model years (2017–2022): 73 manufacturer filings and 1 owner report in NHTSA’s files, across Acadia, Sierra, Terrain, Sierra 2500HD, Sierra 3500HD.
Which GMC model years name C056D
Source: NHTSA manufacturer communications and complaints| Model year | Filed under | Bulletins | Owner reports |
|---|---|---|---|
| 2019 GMC Acadia | Parking Brake | 10 | — |
| 2018 GMC Acadia | Electrical System | 10 | — |
| 2017 GMC Acadia | Parking Brake | 8 | — |
| 2019 GMC Sierra | Parking Brake | 7 | — |
| 2022 GMC Acadia | Power Train | 5 | — |
| 2022 GMC Terrain | Power Train | 4 | 1 |
| 2021 GMC Acadia | Parking Brake | 5 | — |
| 2020 GMC Acadia | Electrical System | 5 | — |
| 2022 GMC Sierra | Electrical System | 3 | — |
| 2021 GMC Sierra | Electrical System | 3 | — |
| 2021 GMC Terrain | Power Train | 2 | — |
| 2020 GMC Terrain | Electrical System | 2 | — |
| 2019 GMC Terrain | Power Train | 2 | — |
| 2018 GMC Terrain | Power Train | 2 | — |
| 2022 GMC Sierra 2500HD | Parking Brake | 1 | — |
| 2022 GMC Sierra 3500HD | Electrical System | 1 | — |
| 2021 GMC Sierra 2500HD | Parking Brake | 1 | — |
| 2021 GMC Sierra 3500HD | Electrical System | 1 | — |
| 2019 GMC Sierra 3500HD | Parking Brake | 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.
GMC filings that name C056D
Source: NHTSA manufacturer communicationsBulletins and campaigns GMC filed with NHTSA whose summary names C056D. Quote the document number at the service desk — it is a diagnosis the maker has already written down.
- PIT5662A Service bulletin2019-04-25 · Electrical System
- This Preliminary information communicates information to diagnose DTC C056D or C056E.
- PIT5662B Service bulletin2019-05-03 · Parking Brake
- This Preliminary information communicates information to diagnose DTC C056D or C056E.
- PIT5662C Service bulletin2019-07-19 · Equipment
- This Preliminary information communicates information to diagnose DTC C056D or C056E.
- PIT5662D Service bulletin2020-01-09 · Parking Brake
- This Preliminary information communicates information to diagnose DTC C056D or C056E.
- PIT5662F Service bulletin2021-08-19 · Electrical System — Adas — Parking Assist — Warning
- This Preliminary information communicates information to diagnose DTC C056D or C056E.
- PIT5662G Service bulletin2022-03-25 · Parking Brake
- This Preliminary information communicates information to diagnose DTC C056D or C056E.
- 22-NA-107 Service bulletin2022-05-20 · Power Train — Automatic Transmission
- This service bulletin provides repair information to correct a customer concern of a Service AWD Message in DIC at Ignition On with DTC C056D Set.
- 22-NA-107 Service bulletin2022-07-21 · Power Train
- This service bulletin provides repair information to correct a customer concern of a Service AWD Message in DIC at Ignition On with DTC C056D Set.
- PIT5662G Service bulletin2022-11-18 · Equipment — Other — Owners/Service/Other Manual
- This Preliminary information communicates information to diagnose DTC C056D or C056E.
What C056D means
Source: SAE J2012 / OBD-IIC056D sits in the generic range of the OBD-II standard, so it means the same thing on every vehicle sold in the United States — but WhichTrim does not carry a definition for it and will not invent one. What is on this page is the record: who named it and on what.
A stored code names the test that failed, never the part that caused it. The record above is what GMC 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 C056D a known problem on GMC vehicles?
It is a documented one: NHTSA's files hold 73 manufacturer filings and 1 owner report naming C056D on 19 GMC model years (2017–2022). 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 GMC models does C056D appear on most?
2019 Acadia (10 documents), 2018 Acadia (10 documents), 2017 Acadia (8 documents).
Does C056D on a GMC 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.