How to troubleshoot & Fix C121C Jeep DTC Code?

The OBD trouble codes come with different levels of implications for the Jeep. You can continue driving with some codes, but some codes need to be removed quickly.

That said, whether the C121C Jeep code will let your Jeep move is a matter of concern. This article will explore this topic and the error code’s fixes. Therefore, let us begin!

What does the C121C Jeep code mean?

The error code C121C in your jeep means that the Torque request signal is denied. It is mainly associated with the ABS module, which suggests that either the Automatic Yaw Control or the Traction Control System is being accomplished.

You can view this code whenever you turn on the ignition in your Jeep. More often, such error codes are detected when the SCP seems invalid. The breakdown of the code below will help you understand better.

  • C – Chassis, includes the functions that are outside the passenger compartment
  • 1 – Manufacturer Specific Number
  • 2 – Injection Nozzles (Torque Request Signal Denied)
  • 1C – Specific Fault Index (Here, the SCP is invalid, resulting in the rejection of the Torque signal)

C121C Code: What causes the Torque request signal to get denied?

The problem behind the error code C121C is either the failure of the PCM or the ABS module. 

As a symptom, it becomes much more evident when you are trying to accelerate heavily and the gear drops Or the brakes become stuck while starting the vehicle suddenly. 

That said, the reasons behind this code getting detected are listed below:

  • Malfunctioning PCM
  • Failure of the Anti-Lock Brake System Module
  • Too much load on the engine

Read Also: How To Troubleshoot & Fix P0441 Jeep DTC Code?

How to troubleshoot & fix C121C Jeep code?

Most OBD codes don’t halt your experience in driving for a while. But when you detect the C121C code in your Jeep, it needs immediate repair. 

The reason is that it might stop your vehicle from getting started or stop it while igniting. 

We’ll address this issue with the solutions for the problems mentioned above. Therefore, go through the fixes carefully as mentioned below:

Diagnose and Clear the Code

Before fixing any faulty component, you should try diagnosing and clearing the code. You can do this with the help of an OBD scanner after connecting with the OBD port in your Jeep. The process in this step is described below:

  • Step 1: Connect the Scanner

Firstly, you must locate the OBD scanner port in your Jeep model. Then, connect your OBD scanner after turning the ignition.

  • Step 2: Press Enter on the Scanner

You will now need to press the enter button on the scanner, which will build the connection.

  • Step 3: Identify the codes

Once the connection is established and the scanning is done, you’ll see the number of codes detected. Press the enter button again, which will take you to the diagnostic menu.

  • Step 4: Read the codes

You’ll see the option for reading the codes in the diagnostic menu. You would need to press the enter button again to choose that option to view the codes. Eventually, it will show you the number of error codes in the system.

  • Step 5: Erase the codes

Navigate back to the diagnostic menu, tap the scroll button, and press enter on erase code option. Once the process is complete, you’ll see on the scanner screen that erasing is done. 

Read Also: How To Troubleshoot & Fix P0456 Jeep Wrangler DTC Code?

Replace the Faulty ABS Module

If reading and erasing the C121C Jeep code doesn’t solve the code from prompting, you would need to inspect whether the ABS module is faulty. 

The steps in this process are listed below:

  • Take a prop and install it in the brake pedal to exert pressure on the brake system
  • Open the hood of your Jeep and navigate to the battery location 
  • Remove the negative end from the battery 
  • Pull up the ABS harness connector and then remove it carefully 
  • Use a pry-like tool to pull up the module block and make it free
  • Take out the bolts with the help of a screwdriver 
  • Take out the old module from the block 
  • Rinse the debris off and dry out the seals in the block
  • Pop on the new module on the block
  • Carry out the steps in reverse order by putting the two bolts back in

Eventually, if the issue is from the faulty ABS module, replacement with the new module will solve the problem.

Read Also: How to troubleshoot & Fix P06dd Jeep Wrangler DTC Code? [Top 4 Fixes]

Replace Malfunctioning PCM

The faulty PCM can trigger certain OBD codes even if the symptoms aren’t present. In this regard, the damage is there in the circuit, which might be due to voltage fluctuations or even due to corrosion, vibration, etc.

That said, repairing the PCM is possible but won’t give you better returns in the longer run. 

For this reason, replacing the faulty PCM is always a better option. Follow the steps mentioned below to carry out the process.

  • Open the hood and locate the vehicle battery
  • Use a 10 mm wrench and disconnect the negative terminal of the battery
  • From the intake, depress the tab and ensure vacuum line removal
  • Remove the MAF sensor, and then also make the line free
  • Identify two 10 mm bolts on the front of the intake and then remove them with a socket
  • Locate and remove the intake box side bolt
  • Loosen all the 8mm hose clamps, and then ensure the removal of the intake assembly
  • Move to the right side of the engine bay of your Jeep and locate the PCM
  • Press the tab and then lift the latch to remove PCM harnesses
  • Navigate to the right side of the PCM and take out the 10 mm bolt
  • Use a nut loosener to remove the 10 mm nut on the lower left corner of the PCM
  • Go to the top left and remove another 10 mm bolt
  • Take out the PCM carefully, as it will be ready for removal
  • Install the new PCM on the same compartment and reinstall all the bolts
  • Tighten the bolts and carry out all the steps in the reverse order

Read Also: How to Troubleshoot & Fix P0128 Jeep Wrangler DTC Code?


Problems with the error codes can often leave you baffled at times. That is why we have added some of the most asked queries about the C121C Jeep code to make you understand better.

How much does it cost to fix the Jeep C121C code?

There isn’t any exact cost for fixing the C121C code in your Jeep. It entirely depends on the reasons behind the cost and the average labor cost in your location if you want a mechanic consultation. But generally, it will range around $850-1100.

Can C121C cause the engine to stall?

Yes, it is possible to have the engine stalled in your Jeep if there is a C121C error code. Because the reason behind this code may result in engine misfiring or power loss, which might have a deep impact on engine stalling.

Can you drive with a C121C Jeep Code?

You may be able to drive with the C121C code in your Jeep. But since it has a high need for repair, you might need help with the vehicle stalling or getting stuck sometimes.

Final Thoughts

Moving with an error code in your vehicle is always a risky prospect. The ABS module or PCM is at fault for the C121C code in your Jeep. 

When it comes to getting rid of the code, you must take help from a certified mechanic, because you may not have the necessary skill, tools, and experience to deal with it.

Read Also: How To Troubleshoot & Fix p1494 Jeep DTC Code?

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