AutoCodes – Generic – C121C

C121C Code - Torque Request Signal Denied

Quick Answer

The Anti-Lock Brake System (ABS) Module monitors the Yaw Control/Traction Control System. Common causes include Faulty Anti-Lock Brake System (ABS) Module, Faulty Powertrain Control Module (PCM). Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: C121C indicates Torque Request Signal Denied.
Common causes: Common causes include Faulty Anti-Lock Brake System (ABS) Module, Faulty Powertrain Control Module (PCM).
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 33,607

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 24, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C121C Description

The Anti-Lock Brake System (ABS) Module monitors the Yaw Control/Traction Control System. The ABS Module sets the OBDII code if engine management relevant for Automatic Yaw Control/Traction Control System control can be accomplished.

OBDII Code C121C - Torque Request Signal Denied - AutoCodes.com — C121C Code - Torque Request Signal Denied

What does this mean?

What are the Possible Causes of the DTC C121C?

Faulty Anti-Lock Brake System (ABS) Module
Faulty Powertrain Control Module (PCM)

How to Fix the DTC C121C?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C121C code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the C121C code?

Need more information on how to fix the C121C code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the C121C code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

C121C Chrysler — Torque Request Signal Denied
C121C Dodge — Torque Request Signal Denied
C121C Jeep — Torque Request Signal Denied
C121C Mitsubishi — Torque Request Signal Denied

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about C121C Code

1. What are the common symptoms of OBDII code C121C (Torque Request Signal Denied)?

- Common symptoms include reduced engine power, poor acceleration, and the vehicle going into limp mode.

2. What can cause the OBDII code C121C (Torque Request Signal Denied) to trigger?

- This code can be triggered by issues with the electronic throttle control system, faulty throttle body, wiring problems, or a malfunctioning engine control module.

3. How can I diagnose the OBDII code C121C (Torque Request Signal Denied) at home?

- You can start by checking the throttle body for any signs of damage or dirt buildup. Inspect the wiring harness for any visible damage, and use an OBDII scanner to retrieve and analyze the error codes.

4. Is it safe to drive with the OBDII code C121C (Torque Request Signal Denied) active?

- It is not recommended to drive with this code active, as it can lead to performance issues and potentially unsafe driving conditions.

5. How can I repair the OBDII code C121C (Torque Request Signal Denied) myself?

- Depending on the root cause, you may need to clean or replace the throttle body, repair any damaged wiring, or replace the engine control module. It's best to consult a professional if you're unsure.

6. Can a bad throttle position sensor cause the OBDII code C121C (Torque Request Signal Denied) to appear?

- Yes, a faulty throttle position sensor can disrupt the signal communication and lead to the code being triggered.

7. Will resetting the OBDII code C121C (Torque Request Signal Denied) make it go away permanently?

- Resetting the code may temporarily clear the error, but if the underlying issue is not addressed, it is likely to reappear.

8. How much does it typically cost to repair the OBDII code C121C (Torque Request Signal Denied) at a mechanic?

- Repair costs can vary widely depending on the specific cause of the code, but expect to pay anywhere from $100 to $500 or more for parts and labor.

9. Can a software update fix the OBDII code C121C (Torque Request Signal Denied)?

- In some cases, a software update from the manufacturer may resolve the code if it is related to a known issue with the engine control module.

10. Is the OBDII code C121C (Torque Request Signal Denied) specific to certain vehicle makes and models?

- While this code may be more common in certain vehicles, it can potentially appear in any vehicle equipped with an OBDII system and electronic throttle control.