Which cars report code C0021?

Code C0021 is named in 13 US owner complaints. Models: 9, model years 2010–2023. Chevrolet Silverado 1500, RAM 2500, Chrysler Pacifica, Dodge Caravan, Dodge Dart.

C0021 code: Brake Booster Performance

Q: What does code C0021 mean?

Brake Booster Performance. How to read C0021: the letter C means chassis (brakes, ABS, steering, suspension); the second digit 0 marks a generic SAE code shared by all makes; the last three characters 021 identify the specific fault.

Code C0021 is named in 13 US owner complaints. Models: 9, model years 2010–2023.

What the code means

Brake Booster Performance. Generic meaning per SAE J2012 (the same for all makes).

How to read C0021: the letter C means chassis (brakes, ABS, steering, suspension); the second digit 0 marks a generic SAE code shared by all makes; the last three characters 021 identify the specific fault.

ABS/ESC codes: wheel speed sensors, the ABS hydraulic unit and pump, brake booster, pressure and yaw sensors. A hit to a wheel or suspension often damages the wheel speed sensor or its wiring, so on a damaged car this code is a reason to inspect the hub, knuckle and control arms, not just swap the sensor.

Key figures

Complaints with this code: 13
Models: 9
Model years: 2010–2023

Which models and years

Models whose owners name this code (9). Years link to the model year problems page.

Model	Years	Complaints
Chevrolet Silverado 1500	2019	4
RAM 2500	2018	2
Chrysler Pacifica	2017	1
Dodge Caravan	2010	1
Dodge Dart	2015	1
Dodge Durango	2014	1
GMC Sierra 1500	2019	1
Jeep Grand Cherokee	2012	1
Jeep Grand Wagoneer	2023	1

Components named together with the code

Component as the owner filed it (one complaint can list several).

Service brakes 12
Electronic stability control 4
Engine 3
Electrical system 2
Fuel/propulsion system 1
Steering 1
Vehicle speed control 1

Complaints by model year

2010 1
2012 1
2014 1
2015 1
2017 1
2018 2
2019 5
2023 1

What to do if an auction car has this code

Inspect the wheel and suspension on the impact side: the wheel speed sensor is often damaged together with the hub or knuckle.
Check whether the ABS and ESC lights stay on after start-up.
After replacing sensors or the hydraulic unit, bleeding and scan tool adaptation may be required.

What owners report

Excerpts of owner complaints in the original wording. Owner statements not verified by the regulator; personal data removed.

System message code C0021-02 brake booster general failure has been displaying on my vehicle when the outside temperature is below freezing because water has seeped into the booster and is freezing which is compromising boost enough to cause the sensor to set the warning message.
Dodge Durango 2014 · 2026-02
17427 miles 68143491aa control anti-lock brake system replaced 68347098ab module anti-lock brake system replaced code found C0021-01 replacement of the hcu and module. 12/30/2019 At 80,460 mi same code and information appeared again.
RAM 2500 2018 · 2024-08
Electrical short on brake booster performance error code C0021 while operating vehicle . Brake pedal became stiff and higher than where I had it . Vehicle making hissing noises and will no longer start due to this error. Safety concern this is not part of a recall list. I nearly crashed.
GMC Sierra 1500 2019 · 2023-11

Related codes

Sources: public official US data (owner complaints) and the SAE J2012 standard. Complaints are owner statements not verified by the regulator. A code from a complaint does not replace a scan tool diagnosis. Data updated 2026-11-10.