AI DamageC121C code in owner complaints
Code C121C is named in 16 US owner complaints. Models: 10, model years 2006–2025.
There is little data for this code or its meaning is ambiguous, so this page is not indexed.
What the code means
This is a manufacturer-specific code: the meaning depends on the make and sometimes on the year.
How to read C121C: the letter C means chassis (brakes, ABS, steering, suspension); the second digit 1 marks a manufacturer code whose meaning is set by the make; the last three characters 21C identify the specific fault.
Codes for engine, transmission, transfer case and hybrid system modules. When valuing an auction car the key question is whether the fault is crash related (cut wiring, damaged radiator) or a known defect of the model.
Key figures
- Complaints with this code
- 16
- Models
- 10
- Model years
- 2006–2025
Which models and years
Models whose owners name this code (10). Years link to the model year problems page.
Components named together with the code
Component as the owner filed it (one complaint can list several).
Complaints by model year
What to do if an auction car has this code
- Separate crash damage (wiring, radiator, mounts) from known model defects: see the model year problems page.
What owners report
Excerpts of owner complaints in the original wording. Owner statements not verified by the regulator; personal data removed.
My local Jeep dealership Service Manager (CF) replied to an email of mine (7/16/26 at 1703) with the following statement: Verified customer concern of check engine light on connect to wytec and found P2173 stored in powertrain control module. Also found C121C stored in ABS module.
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.
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.
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.