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Engine-Codes – Generic – P1203

P1203 Code - Fuel System Failure Caused No. 3 Cylinder Misfire

Quick Answer

The diagnostic trouble code P1203 indicates a fuel system failure that is causing a misfire in the No. Common causes include Faulty fuel injector: A malfunctioning fuel injector may not be delivering the correct amount of fuel to the No, 3 cylinder, leading to a misfire, Clogged fuel filter: A clogged fuel filter can restrict the flow of fuel to the engine, causing a misfire. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1203 indicates Fuel System Failure Caused No. 3 Cylinder Misfire.
Common causes
Common causes include Faulty fuel injector: A malfunctioning fuel injector may not be delivering the correct amount of fuel to the No, 3 cylinder, leading to a misfire, Clogged fuel filter: A clogged fuel filter can restrict the flow of fuel to the engine, causing a misfire.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 07, 2024
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Code P1203 Description

The diagnostic trouble code P1203 indicates a fuel system failure that is causing a misfire in the No. 3 cylinder of the engine. This code is typically found in vehicles with gasoline engines and can have a significant impact on the performance of the vehicle. A misfire occurs when the fuel mixture in the combustion chamber fails to ignite at the correct time, leading to a loss of power, rough idling, and decreased fuel efficiency.

OBDII Code P1203 - Fuel System Failure Caused No. 3 Cylinder Misfire
P1203 Code - Fuel System Failure Caused No. 3 Cylinder Misfire

Common Causes of P1203

  1. Faulty fuel injector: A malfunctioning fuel injector may not be delivering the correct amount of fuel to the No. 3 cylinder, leading to a misfire.
  2. Clogged fuel filter: A clogged fuel filter can restrict the flow of fuel to the engine, causing a misfire.
  3. Malfunctioning fuel pump: A failing fuel pump may not be supplying enough fuel pressure to the No. 3 cylinder, resulting in a misfire.
  4. Fuel pressure regulator issues: A faulty fuel pressure regulator can disrupt the proper fuel pressure in the fuel system, leading to a misfire.

Symptoms of P1203

  1. Rough idling or vibrations: A misfire in the No. 3 cylinder can cause the engine to run rough or produce vibrations that can be felt throughout the vehicle.
  2. Loss of power: The vehicle may experience a decrease in power and acceleration due to the misfire.
  3. Increased fuel consumption: A misfire can lead to inefficient combustion, resulting in higher fuel consumption.
  4. Check Engine Light: The illumination of the Check Engine Light on the dashboard is a common symptom associated with this code.

How to Fix P1203

  1. Diagnose the issue: Use a scan tool to retrieve the trouble code and further diagnose the specific cause of the fuel system failure and misfire in the No. 3 cylinder.
  2. Inspect fuel system components: Check the fuel injector, fuel filter, fuel pump, and fuel pressure regulator for any signs of damage or malfunction.
  3. Replace faulty components: Replace any faulty fuel system components that are causing the issue, such as a malfunctioning fuel injector or clogged fuel filter.
  4. Clear the trouble code: After repairing the issue, clear the diagnostic trouble code from the vehicle's computer to reset the Check Engine Light.
  5. Test drive: Take the vehicle for a test drive to ensure that the misfire has been resolved and that the engine is running smoothly.

Cost to Fix P1203

The typical repair costs for addressing a fuel system failure causing a No. 3 cylinder misfire can range from $200 to $800, depending on the specific cause of the issue and the cost of replacement parts. This estimate includes the cost of labor, which can vary depending on the shop's hourly rates and the amount of time required to diagnose and repair the problem. Additionally, the cost may vary based on the vehicle make and model, as well as any additional repairs or maintenance that may be needed. It's recommended to consult with a qualified mechanic or repair shop for a more accurate estimate based on the specific circumstances.

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Code P1203 Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

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