Fault Code Lookup › Chassis codes › C121C
C121C Chassis · manufacturer code
C121C fault code: what 8 owners reported
C121C is a manufacturer-specific chassis code (chassis: brakes, ABS, stability control, steering and suspension), so its exact definition belongs to the carmaker and is not in the generic OBD-II list. What it meant in practice is below, from 8 complaints owners filed with NHTSA. Updated November 9, 2026.
Owners also write it as C121C00 (the last two characters are the sub-code).
- 8owner reports
- 4car models
- 0mention a crash
- 0mention a fire
- 2012–2025model years
Which cars get code C121C?
Every model whose owners mentioned C121C in a complaint, most reports first. Each year opens that car's full problem report. Popular models collect more reports because more of them are on the road.
Where does C121C show up?
By brand
- Jeep4
- Ram2
- Dodge2
Component the owner filed it under
Is there a recall for C121C?
The others concern the component owners file this code under (Power Train) on the same cars; they may or may not relate to the code. Recall repairs are free; check your VIN at nhtsa.gov/recalls.
Power Train: Manual Transmission: Control Module: Software Chrysler (FCA US, LLC) is recalling certain 2021 Jeep Wrangler and Jeep Gladiator vehicles that were previously remedied under NHTSA recall number 23V-116. The software for the powertrain control module may cause an engine stall, which can result in a loss of drive power.
2021 Jeep Wrangler. Full risk and remedy on each car's report.
Power Train: Automatic Transmission: Control Module (Tcm/Pcm/Tecm) Chrysler (FCA US, LLC) is recalling certain 2021 Ram 1500 vehicles equipped with 5.7L eTorque engines. The powertrain control module software may cause an incorrect fuel mixture condition in the engine, and result in an engine stall.
2021 Ram 1500. Full risk and remedy on each car's report.
Power Train: Clutch Assembly Chrysler (FCA US, LLC) is recalling certain 2018-2023 Jeep Wrangler, and 2020-2023 Jeep Gladiator vehicles equipped with manual transmissions. The clutch pressure plate may overheat and fracture.
2021 Jeep Wrangler. Full risk and remedy on each car's report.
Power Train: Clutch Assembly Chrysler (FCA US, LLC) is recalling certain 2018-2021 Jeep Wrangler and 2020-2021 Jeep Gladiator vehicles equipped with manual transmissions. The clutch pressure plate may overheat and fracture.
2021 Jeep Wrangler. Full risk and remedy on each car's report.
Power Train: Automatic Transmission Chrysler (FCA US LLC) is recalling certain model year 2015-2016 Chrysler Town & Country, Dodge Grand Caravan vehicles manufactured July 31, 2015, to April 18, 2016, 2016 Dodge Journey vehicles manufactured August 17, 2015, to January 29, 2016, and 2016 RAM ProMaster vehicles manufactured August 15…
2016 Dodge Journey. Full risk and remedy on each car's report.
Power Train: Automatic Transmission: Control Module (Tcm/Pcm/Tecm) Chrysler (FCA US LLC) is recalling certain model year 2012-2014 Dodge Charger and Chrysler 300 vehicles manufactured February 15, 2011, to November 27, 2014, and 2014-2015 Jeep Grand Cherokee vehicles manufactured July 16, 2012, to December 22, 2015. The affected vehicles, equipped with an…
2012 Dodge Charger. Full risk and remedy on each car's report.
What happened when owners saw C121C?
8 of the 8 reports, spread across the models above, as the owners wrote them. NHTSA removes names and VINs; long reports are trimmed. CarHooq has not verified individual claims.
…Also found c121c stored in ABS module. Believe ABS code is related to PCM code, cleared codes test drove multiple times. Finally able to get customer concern to duplicate but no data was captured on this failure. We are continuing to drive the vehicle while monitoring data to catch freeze frame data while concern occurs but have not been able to do so far at this time. The condition, when it occurs presents a serious safety concern for the driver and other drivers as it will cause a sever throttle limitation and can cause the vehicle to slow down rapidly. As of 8/9/26, no fix confirmed for my vehicle and the dealership and manufacture are pushing to return my vehicle with confirmed fix. Jeep…
I own a Ram 1500 Big Horn that has repeatedly shut off while driving and entered limp mode, causing sudden loss of power and engine shaking. This has occurred both while driving and while stopped at intersections, creating a serious safety hazard in traffic. The vehicle has been taken to the dealership more than nine times for the same issue, but they initially claimed they could not diagnose the problem because no codes were present. The vehicle recently broke down again and the dealership retrieved diagnostic codes P2172, C121C00, B151A100, and U100300, indicating airflow and CAN bus communication issues. Ram ordered an alternator to fix the truck, but the first part received was defective…
…INDICATED "ABS MODULE DTCS C0037-62.C003A-62 AND C121C-00. FOUND ENGINE WRRE HARNESS CONNECTOR C102 LOOSE. REINSTALLED CONNECTOR C102. CLEARED ALL CODES. PERFORMED EXTENDED ROAD TEST. VERIFY OKAY." -7/6 ~12PM - RECEIVED RECALL NOTICE IN MAIL. SAFETY RECALL M10/NHTSA 12V-197 ABS/ESC WIRING. RECALL CALLS OUT SAME PARTS AS ORIGINAL MALFUNCTION THAT COULD CAUSE CRASH WITHOUT WARNING. -7/7 - 10:30AM. DRIVING AT A HIGH RATE OF SPEED ON HIGHWAY. SAME MALFUNCTION INDICATORS CAME ON WITH ALARMS. NO PLACE TO PULL OFF WITHOUT CAUSING A WRECK. SLOWED DRIVING AND PUT ON HAZARDS. AWAITING TOW TRUCK. DEALER ALERTED. I'M TERRIFIED OF DRIVING THIS CAR THAT HAS UNDER 900 MILES. TWICE THE INCIDENTS OCCURRED IN…
I was driving on the highway and my car started to jerk when I accelerated and hit the brakes. I pulled over to see what was wrong with the car. It hesitated to start back up and when it did it stalled. My ESC light came on and my engine light came on before I pulled over. I was stuck on the side of a busy highway with a car that almost caused an accident when it jerked. Took the car to AutoZone for a diagnostics check and got 3 error codes, P0344, P0128, and C121C-00. Was informed that there are similar issues being reported about cars of the same year, make, and model that was not included in a 2016-2017 recall and that there is an open investigation referring to the camshaft sensor being…
…Started engine drove slowly to the Autozone store to have the diagnostic test done and it showed P2101 power train system throttle actuator A control motor circuit range /performance detected unexpected voltage on the throttle actuator control motor circuit also C121C-00 ABS torque request signal denied Anti-lock Brake System U0401-00 implausible data received from ECM/PCM “A”. System was reset to be able to drive home. 6/16/25 went to start jeep to go to work made a clicking noise check engine light on and the voltage warning sensor flashing and showed Service Electronic Stability Control error would not stay running checked battery cables fuses and restarted engine tried to back out of…
While towing, my truck threw P00AF-00 Turbocharger Boost Control Module "A" Performance and ABS C121C-00 Torque Request Signal Denied codes and I lost power due to turbocharger not engaging. Alarms that were lit included CEL, Service Electronic Throttle Control, and the Stabilizer system. The safety aspect is the loss of power while towing on a highway. The original code was cleared by my hometown dealer and vehicle ran well. 130 miles later it happened again, cleared by dealer in Parkersburg WV On the way home it happened a 3rd time. After parking for half an hour the alarm lights went off and I had full power. A day later the CEL also went off leaving no evidence of a problem on my dash…
MY VEHICLE HAS BEEN IN THE DEALERSHIP APPROX. FOUR TIMES, BECAUSE THE SERVICE ENGINE LIGHT COMES ON, FOLLOWED BY THE TRACTION CONTROL LIGHT. THEY SAID THAT THE CABLE CONNECTION GETS LOOSE AND THEY SOLDERED IT. THIS STARTED ABOUT 20000 MILES AND IS NOW AT 57778 MILES. THIS LAST TIME ON 4-24-2019 THEY SAID THAT IT HAS STORED CODES FOR THE CAM SENSORS ON BOTH BANKS AND TORQUE REQUEST DENIED SIGNAL AND TORQUE MANAGEMENT SIGNAL PERFORMANCE. P2638, C121C, P0344, P0369. THEY SAID THAT IT HAS PCM UPDATE AND THAT THEY PERFORMED THE PCM UPDATE AGAIN AND CLEARED CODES TO SEE IF THEY WOULD COME BACK. VEHICLE DRIVEN 30 MILES AND AND ONE LARGE BUMP IN THE ROAD AND THE LIGHTS TURNED ON AGAIN. THIS HAPPENS…
BOTH TIMES MY PROBLEM OCCURRED I WAS DRIVING DOWN THE HIGHWAY AT ABOUT 70-75 MPH AND THE SWAY CONTROL AND CHECK ENGINE LAMP WOULD BOTH ILLUMINATE. THE VEHICLE WOULD GO INTO POWER DERATE MODE AND YOU COULDN'T ACCELERATE. HOOKED A DIAGNOSTIC CODE READER TO THE VEHICLE AND FOUND CHRYSLER TROUBLE CODES P0369, P2638, AND C121C. HAD TO DO WITH CAMSHAFT SENSOR, AND TRANSMISSION TORQUE REQUEST BEING DENIED. I TOOK IT TO THE DEALERSHIP AND THEY COULDN'T FIND ANY PROBLEM. I HAVE FOUND MULTIPLE PEOPLE ON ONLINE JEEP FORUMS THAT HAVE HAD THE SAME ISSUE OCCUR. THE DEALERSHIP JUST HAD ME GO AND PICK UP MY VEHICLE EXACTLY AS IT WAS WHEN I BROUGHT IT IN. HOPING TO FIND OUT IF ANYBODY HAD THIS ISSUE AND…
C121C: questions drivers ask
What does code C121C mean?
C121C is a manufacturer-specific chassis code (chassis: brakes, ABS, stability control, steering and suspension), so its exact definition depends on the carmaker and is not in the generic OBD-II list. 8 owners reported it to NHTSA, most often for the Jeep Wrangler (4), Ram 1500 (2), Dodge Charger (1); their reports describe what happened.
Which cars get code C121C most often?
In NHTSA owner complaints, C121C is mentioned most for the Jeep Wrangler (4), Ram 1500 (2), Dodge Charger (1), across 4 models and model years 2012 to 2025. Popular models collect more reports because more of them are on the road.
Is there a recall for code C121C?
No NHTSA recall text names C121C directly. 6 recalls on the cars that report this code concern the same component owners name most (Power Train); they may or may not relate to the code. Check your VIN at nhtsa.gov/recalls.
What should I do if my car shows C121C?
Write down when the code appeared and what the car did (warning lights, loss of power, noises, speed, weather). Check your VIN for open recalls at nhtsa.gov/recalls, ask a dealer or independent workshop to read the stored freeze-frame data before anyone clears the code, and keep the repair order. If the car loses power in traffic, stop driving it. CarHooq does not diagnose: these are owner reports and official recall notices, not repair advice.
How this page was made
CarHooq read the text of every owner complaint filed with NHTSA for 19 US and European brands (model years 2012 onwards) and picked out the diagnostic trouble codes owners wrote down. This page lists every mention of C121C (including sub-code forms such as C121C00). Manufacturer codes have no public standard definition, so CarHooq shows only what owners reported. Nothing here is a diagnosis. More answers: the fault code FAQ. Data: NHTSA Office of Defects Investigation (public domain), retrieved November 9, 2026. How CarHooq reports are made.
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