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Home›Trouble codes›U0121› GMC
Diagnostic trouble code · GMC

U0121 on GMC vehicles A module has stopped hearing from the anti-lock brake controller

U0121 is named on 5 GMC model years (2016–2020): 21 manufacturer filings and 0 owner reports in NHTSA’s files, across Sierra, Yukon, Acadia, Terrain.

Network 5 model years 21 manufacturer filings

Which GMC model years name U0121

Source: NHTSA manufacturer communications and complaints
Model yearFiled underBulletinsOwner reports
2016 GMC SierraElectrical System6—
2016 GMC YukonSteering6—
2020 GMC SierraEngine4—
2017 GMC AcadiaElectrical System3—
2016 GMC TerrainEquipment2—

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.

Electrical System 6 Steering 4 Suspension 2 Equipment 2
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GMC filings that name U0121

Source: NHTSA manufacturer communications

Bulletins and campaigns GMC filed with NHTSA whose summary names U0121. Quote the document number at the service desk — it is a diagnosis the maker has already written down.

What U0121 means

Source: SAE J2012 / OBD-II

A module has stopped hearing from the anti-lock brake controller.

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.

From here
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Common questions

Source: NHTSA files and the OBD-II standard

Is U0121 a known problem on GMC vehicles?

It is a documented one: NHTSA's files hold 21 manufacturer filings and 0 owner reports naming U0121 on 5 GMC model years (2016–2020). 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 U0121 appear on most?

2016 Sierra (6 documents), 2016 Yukon (6 documents), 2020 Sierra (4 documents).

Does U0121 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.

Where to go next

pages beside this code
Filed alongside P0300 Another code that appears in the same filings and owner reports as U0121.Filed alongside B3055 Another code that appears in the same filings and owner reports as U0121.Vehicle 2016 GMC Sierra The model year U0121 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.