C0021 fault code: what 12 owners reported

PURCHASED NEW VEHICLE WITH LESS THAN 4,000 MILES WAS RUNNING FINE WHEN PARKED. WHEN IT WAS CRANKED TO GO HOME LISTED ESC FAILURE, SERVICE STEERING COLUMN LOCK, TRAILERING SYSTEM FAILURE, LANE DEPARTURE DISABLED, SPEED LIMITED TO 60 MPH. I WAS ABLE TO GET HOME, BUT THE BRAKES WERE SO HARD THAT IT WAS EXTREMELY DIFFICULT TO STOP. LOCAL DEALER IT WAS PURCHASED THROUGH "FIXED IT" LESS THAN 1,500 MILES LATER I'M HAVING THE SAME ISSUE! OBD HAS THE CODES C0021, C0021, P25A2, P25A2, P0606. I DO NOT FEEL SAFE DRIVING THIS TRUCK! IF THAT ISSUE WERE TO HAPPEN APPROACHING AN INTERSECTION I WOULD HAVE NO WAY OF STOPPING IN TIME. RIDICULOUS.

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. 12/23/2022 No ABS brakes /no speed control continues currently 111,400 miles an indicator lights stay on.

I received P258B warning and further diagnosis came to know that C0021-02 and C1252-92 warnings. While applying breaks i am getting hissing noise and break pedal pushes me back where i have to apply lot of pressure to stop the vehicle. This is happening only when i press the pedals hard. I did diagnosis and noticed that the break vaccum pump fuse gone and replaced the same again it blown. Then realized that that the Vaccum pump it self is not working and the same is ordered and replaced. Now the vaccum pump issue is fixed but still the break pedals are hard and getting hissing noise while applying breaks. Now i may need to change the break booster to get this fixed.

Upon inspection, Power Brake Booster failure, my safety is at Risk due to not having brakes, the issue it has been a confirmed in older models from 2013-2014, recall R63, it has been inspected by an expert and a message pops saying Service Electronic Brake System with code C0021

My 2014 Dodge Durango’s VIN is not listed as impacted by Safety Recall P14/NHTSA 14V-154. However, my vehicle is showing symptoms that match the problem described for that recall. I am requesting an investigation to determine if more VINs than originally impacted are affected by the problem described under the recall. 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. Given the risk of brake failure I have no choice but to arrange for the repair immediately. I will…

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. I had to utilize emergency brake.

…Thankfully even though the light had gone off by the time I got it to the dealer they said the error code was still stored and came back as "C0021-02" or "Brake Booster - General Signal Failure" that likely indicates a failing brake booster BUT the dealer also said I was out of warranty and so no work would be covered even though the brake booster recall work led to this dangerous intermittent failure. I have had multiple occasions recently where my vehicle has taken longer to stop than expected and I never know when its going to happen and so I have to leave very long stopping distances now or else risk rear-ending a stopped vehicle if my brakes randomly stop working effectively (also to…

My brakes stoped working yesterday. The petal went to the floor and there were NO brakes. I was able to put the car in park and stop its movement. The vehicle is at the dealership. This is what they told me- BCSM AND ELECTRONIC BRAKE BOOSTER FAILURE. C0021

REDUCED ABILITY TO BRAKE MY TRUCK ALMOST CAUSED ACCIDENT.. WARNING LIGHT POPPED UP ABS, BRAKE,TRACTION CONTROL WITH WARNINGS GOING ACROSS DASH LIKE BRAKE SYSTEM FAILURE 62 MPH TOP SPEED, SERVICE TRAILER BRAKES. CODES C0021 P0606,& P25A2. HAD UPDATE FOR THIS PROBLEM A COUPLE WEEKS AGO AND IT WAS SUPPOSE TO FIX THIS THE DEALERSHIP SAID OVER THE PHONE WHEN CALLED TODAY. NEVER HAD THIS PROBLEM BEFORE .I AM PRETTY SURE THAT UPDATE JUST UPDATES THE MESSAGING LETTING THE DRIVER KNOW HE OR SHE IS ABOUT TO DIE. TAKING IT INTO DEALER LATER TODAY. ZF TRW INTEGRATED BRAKE CONTROL (IBC) HAD EARLY MANUFACTURING ISSUE LEAVING METAL SHAVING IN THE UNITS. THESE SHAVING WOULD SCORE THE WALLS AND DAMAGE…

In july 2020 the service electronic braking system and service antilock braking system lights and messages started to randomly appear and go away on the dashboard at around 24,000 miles the dealer changed the abs module and controller under warranty on aug 07 2020. Now at 67000 miles on Feb 01 2023 the same messages are happening with code c0021-01 this will be the second brake control module that is failing that will have to be replaced on this vehicle another guy I work with has experienced the same failure on a 2016 ram 2500 around 30000 miles and we are told parts are on back order