5 Steps to Fix Injector Circuit Malfunction

A faulty injector circuit is one of the symptoms of an auto-diagnostic code called P0200. In some cars, the P0202 code pops up. A fuel injector circuit helps to monitor the fuel injector while regulating how much fuel the injector injects into the car. It also regulates when the injector sprays fuel into the system.  

The circuit is said to fail when it delivers low voltage or resistance to the Engine Control Module, ECM also called the Power Control Module (PCM). As a result, the ECM will detect an out-of-range sensor.

How to Diagnose Failing Injector Circuit

  • Connect the diagnostic devices and run a check for the codes present. Make sure you store the freeze frame data linked to the codes.
  • Clear the codes before attempting to fix the faulty injector circuit. 
  • The code that represents a malfunctioning injector circuit is the P0200 or P0202, depending on the vehicle. 
  • Head straight to detect the fault before carrying out any other tests, and there are several ways to do this.
  • Remove the injector connector to access the injector. This way you can test with a solenoid a few things, including the injector resistance. We will also see if there are signals from the injector driver. 
  • If you don’t have access to the injector, you can check the wire from the PCM head straight to the fuse box, and look for a green and black wire. 
  • Disconnect power to the PCM. Get your multimeter to get the continuity and resistance of the wire circulating from the PCM to the connectors
  • Take a comparison rating of the resistance from a new healthy injector. 

After exhausting all the steps above and your rating is perfect go to the next step.

  • Reconnect the plugs and connectors to check for battery voltage for all injectors.
  • Switch the ignition on to check the battery voltage at the injector points. 
  • Use your multimeter to measure the voltage and install the noid lights at each fuel injector, make sure the engine is running while carrying out the test.
  • At this point, the injector circuit will show low voltage and that indicates that you’ll need to get deeper.
  • Remove the intake and read the specifications from the owner’s manual. The injector resistance based on the manufacturer’s spec reading range should be between 11 ohms-13ohms.  
  • Make sure you tape off the ends of the injectors 

How Can I Replace Fuel Injector?

Here are a few steps to take off the bad fuel injector and replace it with a new one. A bad fuel injector replacement is one of the fixes to code P0200. You’ll need a fuel injector puller, a flathead screwdriver, and a few other minor tools. To do this, take the following steps:

Step 1: Look over your injector system

Start by checking your car’s injector system. Study the entire system and it’ll require reading the manufacturer’s specs in your owner’s manual. You should take the proper procedure to relieve the fuel system pressure to avoid damaging the injector system.

Step 2: Pull out the fuel rail

Most cars’ fuel injector system features a fuel rail. It is a component that takes fuel to the injector. First take the fuel rail off by disconnecting the fuel rail lines, screws, and bolts that connect the rail to the injector. Some cars have wiring passed over the rail. Follow the right procedure to remove the wires. 

Step 3: Disconnect the fuel injector components  

Now that the fuel delivery rail is out of the way, the next thing is to disconnect the fuel injector fasteners. First, remove the fuel lines that are connected on top of each of the injectors. Then disconnect the fuel plugs that are fastened to the wiring harness by springy wires. You can remove the springy wires with a flathead screwdriver.  

Step 4: Yank the fuel injector  

After pulling out the fuel injector fastening components, you’ll be face-to-face with the fuel injector itself. While there are several ways to yank the fuel injector, using a puller will be your best bet. This way, you can avoid causing severe damage to the engine, the fanny, and other delicate parts.

Slip the injector puller under the lip of the injector casing. Allow the injector to pop out and sinks gently into a hole inside the intake manifold. Leave this hole open because you’ll need it to install the new injector. 

Step 5: Install a new injector

Take off the old injector and install a new one. Don’t force the new injector into the open hole and follow the steps in reverse order. 


Can I drive my car with a failing injector?

Yes, you can drive a car with a faulty injector, but for a limited distance. However, doing that can potentially damage other components of your car and cause you to pay dearly for the wear and tear of vital car parts. Driving on a malfunctioning injector can make the engine flood and the car stall. Plus, it can also lead to fuel pre-ignition, and lots more.

What Code Does the Fuel Injector issue pop up?

There are a few issues that can flag the P0200 code. It could be an ECU problem, a short in the wiring, or a faulty injector circuit. Connection issues can also trigger the code. There are several fixes to the code. You can fix any connection issues, tighten loose wires and replace bad ones, or replace the ECM or PCM. Lastly, take off the fuel injector and replace it with a new one. I’ll later explain the steps to replace the fuel injector. 

Final Thoughts 

An injector circuit fault can cause a whole lot of damage to your vehicle. Once the circuit gets bad, it’s time to fix it. You can diagnose as stated above, using a general test and/or manufacturer-specific ECM test. Even if you need to drive with a failed fuel injector, don’t let the problem stay too long. A quick response to an auto issue is best for the health of your car and your finances. I hope you’ll find this article helpful. 

  • James Smith

    I'm James Smith, a car enthusiast and a content writer for Daily Car Tips. I have a passion for all things cars, from classic muscle cars to the latest electric vehicles. When I'm not writing about cars, you can usually find me tinkering with my car or checking out the latest automotive trends.

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