Engine-CodesGeneric – P204D

P204D Code - Reductant Pressure Sensor Circuit High

Quick Answer

The P204D diagnostic trouble code (DTC) refers to the Reductant Pressure Sensor Circuit High. Common causes include Faulty Sensor: The reductant pressure sensor itself may be faulty and providing incorrect readings, Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the sensor can cause circuit high readings, SCR System Malfunction: Problems with other components of the SCR system, such as the DEF injector or pump, can impact the pressure sensor circuit. 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
P204D indicates Reductant Pressure Sensor Circuit High.
Common causes
Common causes include Faulty Sensor: The reductant pressure sensor itself may be faulty and providing incorrect readings, Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the sensor can cause circuit high readings, SCR System Malfunction: Problems with other components of the SCR system, such as the DEF injector or pump, can impact the pressure sensor circuit.
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.
Table of contents Created and updated by William Orellana on Sep 10, 2024
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Code P204D Description

The P204D diagnostic trouble code (DTC) refers to the Reductant Pressure Sensor Circuit High. This code indicates that there is an issue with the reductant pressure sensor circuit in the vehicle's selective catalytic reduction (SCR) system. The SCR system is responsible for reducing harmful emissions in diesel engines by injecting a urea-based solution (DEF - Diesel Exhaust Fluid) into the exhaust stream. The reductant pressure sensor is a crucial component of this system, as it measures the pressure of the DEF to ensure proper operation.

OBDII Code P204D - Reductant Pressure Sensor Circuit High
P204D Code - Reductant Pressure Sensor Circuit High

Common Causes of P204D

  1. Faulty Sensor: The reductant pressure sensor itself may be faulty and providing incorrect readings.
  2. Wiring Issues: Corrosion, damage, or loose connections in the wiring harness connected to the sensor can cause circuit high readings.
  3. SCR System Malfunction: Problems with other components of the SCR system, such as the DEF injector or pump, can impact the pressure sensor circuit.
  4. Software Glitch: Occasionally, a software issue within the vehicle's engine control module (ECM) can cause false high voltage readings from the sensor.

Symptoms of P204D

  1. Check Engine Light: The most common symptom associated with this code is the illumination of the check engine light on the vehicle's dashboard.
  2. Reduced Power: The vehicle may experience a decrease in power and performance, especially during acceleration.
  3. Poor Fuel Efficiency: An increase in fuel consumption can be a sign of issues with the reductant pressure sensor circuit.
  4. Failed Emissions Test: If the vehicle is subject to emissions testing, it may fail due to increased emissions caused by the malfunctioning SCR system.

How to Fix P204D

  1. Diagnose the Issue: Use a diagnostic scanner to read the DTC and determine the specific cause of the high reductant pressure sensor circuit.
  2. Inspect Wiring: Check the wiring harness for any signs of damage, corrosion, or loose connections. Repair or replace as necessary.
  3. Test Sensor: Test the reductant pressure sensor to verify if it is functioning correctly. Replace if found to be faulty.
  4. Check SCR System: Inspect other components of the SCR system to ensure proper operation and address any issues that may be affecting the pressure sensor circuit.
  5. Clear Codes: After making the necessary repairs, clear the DTC from the vehicle's ECM to reset the check engine light.

Cost to Fix P204D

The cost of repairing a high reductant pressure sensor circuit can vary depending on the cause of the issue and the specific vehicle make and model. Generally, the cost of parts for this repair can range from $100 to $300, with labor costs adding an additional $100 to $200. Overall, the total repair cost can be expected to fall within the range of $200 to $500. It's important to note that diagnostic time and labor rates at auto repair shops can vary, so it's advisable to check with local shops for a more accurate estimate.

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Code P204D 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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