Question: C121C Torque Request Signal Denied? (Causes and Fixes)

Is your Jeep displaying the “C121C Torque Request Signal Denied” notification, and you can’t figure out what it means?

While alerts on your vehicle’s dashboard are scary, they signify the need for immediate attention. Some are easy to clear with a diagnostic tool, while others require fixing underlying problems. If you see the C121C code, don’t ignore it, as doing so can cause more harm to your vehicle.

So, what does this notification mean, and how can you troubleshoot it?

Herein, I discuss the C121C code Jeep, its causes, symptoms, and effective fixes. You’ll also know if driving with the C121C code is safe.

Question: What Does Torque Request Signal Denied Mean?

This alert on your Jeep’s dash relates to the Antilock Brake System (ABS) module. It appears when the ABS module rejects the torque request signal from the Power Control Module (PCM). The C121C code means the ABS module has determined that an issue with the powertrain will inhibit the proper functioning of the Traction Control System (TCS).

The TCS uses yaw rate sensors that monitor the tires to detect a loss of traction. Traction control will also control the electronic throttle and lower the RPM when needed.

If there’s a problem with the ABS module or the PCM preventing the activity of the TCS, you’ll see the C121C code Jeep notification on the dash. Below is a breakdown of this code to help you understand it better:

  • C: Chassis
  • 1: Manufacturer specific number
  • 2: Injection nozzles
  • 1C: Specific fault index that indicates the torque request signal’s rejection due to system issues.

Answer: Causes of the C121C Code Jeep

The C121C Jeep notification may appear on the dash for three reasons. It could be a result of:

  • Antilock Brake System Module failure
  • Malfunctioning PCM
  • Excessive load on the engine

The alert may appear when you accelerate heavily or when starting your Jeep. You’ll likely see this trouble code on Jeep models like the Grand Cherokee, Patriot, Commander, Wrangler, and Compass. Let’s detail these causes to understand how they trigger the warning notification.

Antilock Brake System Module Failure

The ABS module monitors the Antilock Braking System by collecting data from the wheel sensors and hydraulic brake system.

This data will help the ABS module determine the right time to release brake pressure. This activity prevents the locking of wheels while driving, which may push your car into a skidding motion.

The ABS module can malfunction due to excessive wear or damage. If the module is okay, the issue may stem from faulty wheel speed sensors, wiring, or connections. The wheel speed sensors can become corroded or damaged over time and fail to transmit signals.

Moreover, the ABS connectors get loose or corroded over time and inhibit the proper functioning of the ABS. Wires can also break or melt due to electrical shorts, triggering the problem.

If your Jeep has an ABS module failure, the TCS won’t do its job, causing the torque request signal denied notification to appear. The following symptoms may accompany this alert:

  • Engine starting problems
  • Weaker braking capacity
  • Antilock Braking System warning light
  • Engine stalling
  • Flickering headlights

Malfunctioning Power Control Module (PCM)

The PCM manages the functions of the engine and transmission system to ensure the vehicle’s smooth operation. It receives information from sensors around your car to ensure all systems work as expected.

The PCM can malfunction if there’s an issue with one of these systems, wiring, connections, or sensors. As a result, the TCS fails, leading to the warning message on your Jeep’s dash. You may also notice the following symptoms:

  • Engine starting problems
  • Warning light
  • Less fuel efficiency
  • Engine misfires

Excessive Load on Engine

If the load exceeds the rated engine load, the engine’s ability to produce the required torque decreases. Moreover, the Antilock Braking System may fail to work at high speeds. This issue may cause the ABS module and PCM to malfunction, leading to the alert message on the dash.

If engine load is the problem, you may notice the following symptoms:

  • Check engine light
  • Weak acceleration
  • Weak braking capacity

Answer: How To Fix Code C121C

The best way to address the C121C code Jeep is to determine the cause. If the load exceeds the rated load for your Jeep’s engine, try reducing it. You can check your Jeep’s owner’s manual for the rated load.

If the notification stays on the dash after reducing the load, try clearing the error code with an OBD scanner. Connect the scanner to your Jeep model’s OBD port. Navigate the menu to view the error codes detected from your vehicle.

Your diagnostic tool has an option to read and erase the error codes. You only need to select the erase option and press ENTER to delete the codes. This process will help clear the C121C torque request signal denied alert.

However, if your Jeep has problems with the ABS Module or the PCM, the notification will appear after driving for a while. You must fix the underlying cause to clear this message. The problem is either related to the ABS module or the PCM.

Below are ways to get this job done.

Fix the ABS Module

A faulty ABS module may trigger the error message on the dash. Before considering a replacement, examine the components making up the ABS module.

Defective connectors and wiring will cause the ABS module and the PCM to malfunction. Locate the connection points and wiring from the ABS module to the PCM. If you find any loose connectors, reconnect them properly. Additionally, replace any broken, frayed, or damaged wiring.

The ABS module also comprises the wheel speed sensors. The sensors may act up if they get too dirty. In this case, locate the ABS sensors and use a torque wrench to remove them. Then, use soapy water and a rag to wipe away the dirt on the sensors.

If cleaning the sensors won’t work, test each sensor on the wheels with a multimeter to determine the problematic one. You can replace a damaged sensor if necessary.

The ABS module could be faulty if these fixes don’t clear the C121C code. You can replace the defective ABS module at home if you have basic skills and tools. These steps will help you replace the module:

  • Park your Jeep on a level ground and turn off the engine.
  • Open the hood to locate the battery and the module.
  • Disconnect the battery’s negative terminal.
  • Locate the ABS harness connector and pull it up to remove it.
  • Use a screwdriver to loosen the bolts holding the module in the block.
  • Remove the old module and clean the seals in the block.
  • Install a new module, reinstall the bolts, and tighten them. Then, connect the ABS harness connector.

If the ABS module is the problem, installing the new module will clear the warning notification. However, if the C121C Jeep code won’t go, a faulty PCM could be the cause.

Fix the PCM

The power control module can malfunction due to electrical shorts, corrosion, or vibrations. If you’re sure the PCM is the culprit, take your Jeep to an authorized mechanic for fixing. The mechanic can repair the PCM, depending on the cause.

Replacing the PCM is the best option if it is faulty beyond repair. Unlike the ABS module, replacing the PCM is a complicated process. Allow your mechanic to examine the PCM and replace it if necessary.

Question: Can You Drive Your Jeep with the C121C Code?

It’s possible to drive your Jeep with the C121C code, depending on the causative factor. You may drive the car if the error code stems from faulty sensors, wiring, or connections. However, driving with this code may aggravate the problem, leading to complete damage to the ABS module or the PCM.

You’ll need professional assistance if your Jeep stalls or gets stuck due to the C121C Jeep Code.

Wrapping Up

The C121C torque request signal denied notification indicates a problem with the ABS module, PCM, or engine load. To clear this alert, you must determine and fix the root problem. Sometimes, deleting the C121C code Jeep is possible using a diagnostic tool.

If fixing the ABS module or the PCM seems daunting, get the help of a certified mechanic. Your mechanic may repair the defective parts or replace the entire system.

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