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Summary
  • DTC P0203 stands for “Injector Circuit/Open – Cylinder 3.” It’s logged when the PCM detects an issue with the fuel injector or its wiring.
  • A logged P0203 can cause your vehicle to exhibit symptoms, such as an illuminated check engine light, decreased engine performance, and increased fuel consumption.
  • Problems that could trigger this code include Fuel injector 3 damage or failure, wiring issues, and PCM failure.

Say you’re using your OBD-II scan tool to check your vehicle and the P0203 code appears. What does it signify? This guide will help you learn more about what the P0203 code means, as well as its possible causes and common symptoms, so that you can troubleshoot it as soon as possible.

What Does the P0203 Code Mean?

Diagnostic trouble code (DTC) P0203 stands for “Injector Circuit/Open – Cylinder 3.” The powertrain control module (PCM) may set this code if it has detected a potential error in the injector or the injector wiring. It may also register this code if it can’t control the fuel injector.

car fuel injector wiring diagram
Fuel injector wiring diagram | Image Source: Richard McCuistian

For example, when the injector on an MPI unit is grounded, the injector pintle raises off its seat, and fuel flows during that very brief instant (1-5 milliseconds). When the ground to the injector coil is released, the pintle spring snaps it back against its seat, fuel flow stops, and the collapsing magnetic field induces a spike of about 50 volts that travels back toward the ECM/PCM on that ground trigger circuit, which is designed to handle those voltage spikes.

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The PCM is equipped with special transistors called “drivers” that switch the engine’s fuel injectors on and off. When an injector is switched on or off, the PCM expects the voltage and resistance to stay within a certain range.

Or, if it doesn’t sense 12 volts on the trigger side of the injector (coming through the injector coil from the opposite side), it can use that information to store the P0203 code. It varies from OEM to OEM. Likewise, if the PCM detects that the voltage and the resistance do not fall within the expected values, the P0203 code is set.

You can find more useful information in our technical discussion about fuel injection systems.

Note: The definition of code P0203 may be different depending on the vehicle manufacturer. Consult the appropriate repair manual or repair database for the exact code definition.

What are the Possible Causes of the P0203 Code?

Like all OBD-II codes, the P0203 error code has several possible causes. These include:

  • Fuel injector 3 damage or failure
  • Wiring issues (e.g., fuel injector 3 control circuit is open, shorted to ground, or shorted to voltage)
  • PCM failure

What are the Common Symptoms of the P0203 Code?

Below are some of the most common symptoms of the P0203 code:

How to Diagnose the P0203 Code

Diagnosing error codes like the P0203 is challenging because you need to narrow down the root cause from a list of possible causes. As such, you may need help from a seasoned mechanic or technician to find out what triggered this code in your vehicle.

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If you want to know more about this code, there are a few resources that explain this code’s diagnostic process in more detail.

Below is a video that illustrates how the P0203 error code might be diagnosed:

How to Fix the P0203 Code

Many diagnostic trouble codes share the same symptoms, possible causes, and areas of concern. This is why they don’t have a single cure-all solution. Before you can even fix the P0203 code, you need to determine the exact root cause and the prescribed repair procedure for your specific vehicle.

Luckily, there are repair manuals and repair databases to help you figure out what needs to be done. One of the most reliable sources is a vehicle-specific repair manual, which is written for your vehicle’s exact make and model. A repair manual also contains detailed repair information, as well as illustrations and diagrams to help you better understand the issue.

If you don’t have a lot of experience diagnosing or fixing trouble codes, it’s best to leave the work to a professional mechanic, so that you can avoid problems and more expensive repairs down the line.

Other Notes About P0203

The P0203 code is considered severe. Driving while your vehicle has triggered this code without having it repaired is highly discouraged. If you encounter this code, we recommend taking your vehicle to a nearby repair shop for diagnosis.

Where to Get Top-Notch Fuel Injectors to Clear Code P0203

Don’t let your vehicle hang out in the garage for days because of the issues caused by the P0203 code. If a malfunctioning fuel injector is the culprit, don’t put off replacing it. For a wide selection of high-quality fuel injectors to choose from, look no further than CarParts.com.

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To start shopping, visit our website and fill out our vehicle selector to narrow down your search to compatible fuel injectors. Then, use the search filters to view the ones that match your preferred brand, price range, and more.

If you need your replacement part as soon as possible, we have you covered. We have distribution centers strategically located across the country to ensure fast and efficient shipping. We also have a 24/7 customer service team ready to assist you anytime if you have questions about your order or our products.

All our parts passed stringent quality control tests, so you can be sure that they function just like your factory unit. They also come at unbeatable prices to help you get the best value for your money.

Take a look at our selection of fuel injectors now and order what you need today!

Shop this Project

Replacement – Fuel Injector, with Red Connector
, P0203 Code: Injector Circuit / Open – Cylinder 3
$17.49 Price and rating may change from the time content is published.
Replacement – Fuel Injector, Blade Type, 2-Prong Male Terminal, Includes O-Ring
, P0203 Code: Injector Circuit / Open – Cylinder 3
$21.54 Price and rating may change from the time content is published.
Replacement – Fuel Injector – New, Sold individually
, P0203 Code: Injector Circuit / Open – Cylinder 3
$17.49 Price and rating may change from the time content is published.
About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

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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