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Engine-Codes – Generic – P203D

P203D Code - Reductant Level Sensor Circuit High

Quick Answer

The P203D diagnostic trouble code (DTC) refers to a Reductant Level Sensor Circuit High. Common causes include Faulty reductant level sensor, Wiring or connection issues in the sensor circuit, Contaminated or incorrect reductant fluid. 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
P203D indicates Reductant Level Sensor Circuit High.
Common causes
Common causes include Faulty reductant level sensor, Wiring or connection issues in the sensor circuit, Contaminated or incorrect reductant fluid.
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 11, 2024
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Code P203D Description

The P203D diagnostic trouble code (DTC) refers to a Reductant Level Sensor Circuit High. This code is typically found in diesel vehicles equipped with a selective catalytic reduction (SCR) system. The reductant level sensor is a crucial component of the SCR system, responsible for monitoring the level of diesel exhaust fluid (DEF), also known as reductant. The reductant is injected into the exhaust stream to help reduce harmful emissions, specifically nitrogen oxides (NOx).

OBDII Code P203D - Reductant Level Sensor Circuit High
P203D Code - Reductant Level Sensor Circuit High

Common Causes of P203D

  1. Faulty reductant level sensor
  2. Wiring or connection issues in the sensor circuit
  3. Contaminated or incorrect reductant fluid
  4. Corrosion or damage to the sensor or its wiring
  5. Electronic control module (ECM) failure

Symptoms of P203D

  1. Check engine light illuminated
  2. Reduced engine performance
  3. Failed emissions test
  4. Increased fuel consumption
  5. Black smoke coming from the exhaust

How to Fix P203D

  1. Begin by diagnosing the exact cause of the high voltage signal in the reductant level sensor circuit using a diagnostic scanner.
  2. Inspect the wiring and connections for any signs of damage, corrosion, or loose connections. Repair or replace any damaged components as needed.
  3. Test the reductant level sensor itself to determine if it is functioning correctly. Replace the sensor if it is found to be faulty.
  4. Verify that the reductant fluid in the tank is the correct type and not contaminated. Drain and refill the tank if necessary.
  5. Clear the DTC from the vehicle's ECM memory and perform a test drive to ensure the issue has been resolved.

Cost to Fix P203D

The repair costs for addressing a P203D DTC can vary depending on the specific cause of the issue. In general, you can expect to pay anywhere from $150 to $500 for parts and labor. Keep in mind that these costs are just estimates, and prices may vary based on factors such as location, vehicle make and model, and the labor rates of the auto repair shop. It's recommended to consult with a professional mechanic to get a more accurate estimate for your particular situation.

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Code P203D 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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