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Fuel injectors spray atomized fuel into the cylinders or intake manifolds of internal combustion engines with an electronic fuel injection system. To activate the injector, the computer that controls the engine energizes the injector’s driver. An energized driver forms a closed circuit that moves the injector’s valve to the open position.

If the engine control module (ECM) or powertrain control module (PCM) detects a problem with the cylinder four fuel injector or its circuit, it will set a P0204 code.

What Does the P0204 Code Mean?

The Diagnostic Trouble Code (DTC) P0204 indicates “Injector Circuit Problem—Cylinder 4.” 

Each fuel injector possesses a solenoid-operated valve that allows pressurized fuel to flow out of the part. A special transistor called a “driver” controls the valve. Energizing the driver creates a closed circuit and moves the valve to an open position.

technician inspects one fuel injector
Fuel injectors spray atomized fuel into the cylinders or intake manifolds of internal combustion engines with an electronic fuel injection system.

The engine computer, which is often referred to as the powertrain control module (PCM), keeps track of injector operation. A dormant injector will show a voltage close to battery voltage while an active one will pull its voltage to a “low” value near zero. If the injector’s voltage does not match the voltage expected for its state, the PCM will set the P0204 code.

The PCM also measures the circuit’s electrical resistance. It will set a P0204 code if the resistance is much higher or lower than it should be.

Read our technical discussion about fuel injection for a broader background on how codes like P0204 can come about.

Note: The definition of code P0204 may differ according to the vehicle manufacturer. Check the right repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0204 Code?

  • Worn-out or faulty fuel injector
  • Powertrain Control Module (PCM) issue 
  • Circuit problems, such as damaged wires and loose connections 

What are the Common Symptoms of the P0204 Code?

  • Decreased engine performance, including:
    • Engine misfire
    • Engine runs roughly
    • Reduced acceleration
  • Increased fuel consumption
  • Check engine light switches on

How to Diagnose the P0204 Code

A DTC P0204 is a generic trouble code that may be logged in vehicles from different auto manufacturers. While these vehicles may display similar triggers and symptoms, the steps for diagnosis and repair may differ according to their make and model.

If you’re not sure about your ability to run diagnostic tests on your vehicle, consider bringing it to a professional mechanic. Otherwise, you might consider diagnosing the issue yourself. To help you get started, here is a video  that may give you an idea of what the process might involve:

How to Fix the P0204 Code

Attempting to fix a P0204 code may prove frustrating if you lack the right tools and know-how to test the fuel injector and its circuit. In most cases, it’s best to leave the job to professionals.
For DIYers with advanced technical knowledge and hands-on experience who prefer to test and replace their vehicle’s fuel injector on their own, it will be helpful to rely on repair manuals or repair databases.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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