P121B Code In Dodge Charger: What Does It Mean?

P121B code in Dodge Charger is a manufacturer-specific code that shows that the active exhaust actuator is not working correctly. Active Exhaust Valve actuator 2 is usually located on the passenger’s side.

The active exhaust valve system regulates the flow of exhaust gasses through the exhaust system. It comprises a series of valves that can be opened and closed to allow exhaust gasses to pass through or be redirected back into the engine.

I will give you a detailed overview of the meaning of the p121B code in your Dodge Charger, its symptoms, and how to fix it.

Causes And Symptoms of p121b Code in Dodge Charger

If you’re hearing engine noises while driving, the source is probably a mechanical butterfly valve bind-off. This problem happens when the butterfly valve, which controls the flow of air and fuel into the engine, becomes stuck in the closed position. This can cause a variety of engine noises, including knocking and ticking.

A broken transmission spring might produce a slight spark knock or engine misfiring. 

The transmission spring absorbs and distributes the force imparted to the transmission, and if it breaks, it might result in engine misfiring and decreased performance. In addition to engine misfiring, a broken transmission spring might cause issues shifting gears and illuminate the check engine light.

If your vehicle’s check engine light is illuminated, the problem could be an active exhaust valve 2 actuator that is not properly mounted or positioned. A defective actuator could also be the source of a Malfunction Indicator Lamp (MIL) illumination.

The following table shows the causes and symptoms of the p121b code in your Dodge Charger.



Engine noisesMechanical butterfly valve bind-off
Slight spark knock or engine misfiringTransmission spring broken
Check engine light illuminatesActive exhaust valve 2 actuator not installed/positioned properly
Malfunction Indicator Lamp (MIL) IlluminationFaulty actuator

So, what is the p121b code? 

  • P- refers to the engine, transmission, fuel system, and accessories.
  • 1-indicates that the code is specific to the car manufacturer.
  • 2-refers to the mechanism for fuel or air metering injection
  • 1- problem with active exhaust actuator
  • b- right side actuator

As mentioned before, when the p121b code pops up, it indicates a problem with the actuator, the active exhaust valve 2, or with the system controlling it.

What Is An Active Exhaust Actuator In Dodge Charger?

To better understand the p121b code, let’s answer this question; “What is an active exhaust actuator?” The best way to respond is by showing you a diagram of how it looks.

dual-mode exhaust system diagram

dual-mode exhaust system

The left diagram depicts a Dodge dual-mode exhaust system, while the diagram on the right depicts the actuators. Active exhaust utilizes a pair of electrical valves situated towards the vehicle’s rear.

The purpose of Active Exhaust Valves is to lower the exhaust noise. Each exhaust pipe consists of two butterfly valves. On each valve, there is an actuator mounted to it. 

When installing the actuator, it must be properly connected to prevent any damage to the valve. Each actuator has a specific internal identification number. The PCM uses this identification number to determine the location of each actuator.

Next, a transmission spring connects the valves to the actuator. The purpose of a transmission spring is to lower the transfer of heat between the actuator and the exhaust valves. Let’s now concentrate on the p121B code.

How Do I Fix p121b Code on Dodge Charger

A trained automotive mechanic should inspect and repair the active exhaust valve to remedy this issue. However, if you are an experienced do-it-yourselfer, you must follow these steps.

Monitor the connection and terminals of the actuator for the active exhaust valve 2

  • Step 1: Turn the ignition off
  • Step 2: Examine the connector for the Exhaust Valve 2 harness for damage caused by the debris
  • Step 3: Examine the Active Exhaust Valve 2 assembly’s harness connector for any pushed-out, damaged, corroded, or bent terminals
  • Step 4: If there are any issues with the connector or terminals, fix the damaged terminal or connect and secure the harness connector for the Active Exhaust Valve 2 Assembly.
  • Step 5: Then, recheck for the diagnostic error code.

Check the transmission’s active exhaust valve actuator spring

  • Step 1: You must remove the actuator from the Active Exhaust Valve.
  • Step 2: Verify that the actuator’s spring is undamaged and correctly installed.
  • Step 3: If the transmission spring is defective, it must be replaced or reinstalled correctly, and you must recheck the diagnostic trouble code test.

Check that the butterfly valve is operating correctly

  • Step 1: Manually move the valve from one end to the other.
  • Step 2: The butterfly valve should be able to move freely between its stops without binding.
  • Step 3: Replace the valve, oil it, and then perform a DTCs test if it is not freely movable.

Monitor the exhaust actuator

  • Step 1: Remove and then reinstall the actuator.
  • Step 2: Then, activate the Active Exhaust Valve 2 Actuator to any percentage using the scan tool.
  • Step 3: If the actuator readily moves the valve, either the positioning of the valve to the actuator was incorrect or the valve was stuck.
  • Step 4: If the actuator cannot freely move the valve, it must be replaced.

Substituting the actuator

  • Step 1: Remove the old actuator and install a replacement.
  • Step 2: Ensure you connect all disconnected harness connectors.
  • Step 3: Delete all error codes via a scan tool.
  • Step 4: Engage the ignition.
  • Step 5: Repeat any DTC tests.

Examine the PCM and its components

  • Step 1: Unplug every PCM component harness connector.
  • Step 2: Examine the PCM harnesses, component connectors, and terminals for any signs of damage, corrosion, or poor connection.
  • Step 3: Repair any broken parts.
  • Step 4: Reconnect each connector on the PCM harness.
  • Step 5: Delete all DTCs using a scan tool.
  • Step 6: Turn on the ignition and observe to see if the error code reappears.
  • Step 7: If the error persists, you must replace the complete PCM system.

Here is a video that shows the p121b code on a Dodge Charger.


Here are other related questions-

Q: How much does it cost to fix p121b code?

Labor costs go for about $100-$180, depending on the shop’s location. Parts will go for $387-$500, depending on whether they are OEM or aftermarket parts.

Q: Can I drive my Dodge Charger with a p121b code?

Yes, you can. However, you risk damaging your engine, so it is recommendable to take the vehicle for the device as soon as possible.

Before wrapping up, you may also check-

  1. Meaning and Solution of P0430 Code in Dodge Charger
  2. How To Fix U0100 Code on Dodge Charger


The P121b code Dodge Charger indicates a problem with the Active Exhaust Valve 2 Performance. It shows that the active exhaust actuator has an issue.

You need to diagnose the PCM, transmission spring, actuator itself, and exhaust valves to fix it. If you notice any damage or poor connection in the wiring or terminals, you must fix it to clear the code.


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