Engine-CodesGeneric – P20A8

P20A8 Code - Reductant Injection Air Pressure Control Valve Circuit Low

Quick Answer

The diagnostic trouble code P20A8 refers to an issue with the reductant injection air pressure control valve circuit being detected as low. Common causes include Faulty Control Valve: The reductant injection air pressure control valve itself may be faulty and in need of replacement, Wiring Issues: Problems with the wiring connecting the control valve to the control module can cause this code to trigger, Control Module Malfunction: A malfunctioning control module that controls the operation of the valve can also be a potential cause. 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
P20A8 indicates Reductant Injection Air Pressure Control Valve Circuit Low.
Common causes
Common causes include Faulty Control Valve: The reductant injection air pressure control valve itself may be faulty and in need of replacement, Wiring Issues: Problems with the wiring connecting the control valve to the control module can cause this code to trigger, Control Module Malfunction: A malfunctioning control module that controls the operation of the valve can also be a potential cause.
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 16, 2024
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Code P20A8 Description

The diagnostic trouble code P20A8 refers to an issue with the reductant injection air pressure control valve circuit being detected as low. In vehicles equipped with a selective catalytic reduction (SCR) system, the reductant injection air pressure control valve plays a crucial role in controlling the flow of reductant (such as diesel exhaust fluid) into the exhaust stream to reduce harmful emissions. When this valve circuit is detected as low, it indicates that there may be a problem with the valve itself, the wiring, or the control module.

OBDII Code P20A8 - Reductant Injection Air Pressure Control Valve Circuit Low
P20A8 Code - Reductant Injection Air Pressure Control Valve Circuit Low

Common Causes of P20A8

  1. Faulty Control Valve: The reductant injection air pressure control valve itself may be faulty and in need of replacement.
  2. Wiring Issues: Problems with the wiring connecting the control valve to the control module can cause this code to trigger.
  3. Control Module Malfunction: A malfunctioning control module that controls the operation of the valve can also be a potential cause.
  4. Electrical Faults: Any electrical faults within the circuit can disrupt the proper functioning of the valve and trigger this code.

Symptoms of P20A8

  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 loss of power or decreased acceleration due to the reductant injection air pressure control valve not functioning correctly.
  3. Poor Fuel Efficiency: A decrease in fuel efficiency may be noticed as a result of the engine not operating at optimal levels.
  4. Failed Emissions Test: If the issue is not addressed, the vehicle may fail emissions tests due to increased emissions output.

How to Fix P20A8

  1. Diagnose the Issue: Use a diagnostic scanner to retrieve the specific trouble code and pinpoint the exact cause of the problem.
  2. Inspect Wiring and Connections: Check the wiring and connections related to the reductant injection air pressure control valve for any damage or corrosion.
  3. Test Control Valve: Test the functionality of the control valve to determine if it is operating correctly or needs to be replaced.
  4. Check Control Module: Inspect the control module for any signs of malfunction and replace if necessary.
  5. Clear Codes and Test Drive: Clear the diagnostic trouble codes, reset the vehicle's computer, and test drive to ensure the issue has been resolved.

Cost to Fix P20A8

The typical repair costs for addressing a reductant injection air pressure control valve circuit low issue can vary depending on the specific cause of the problem. In general, the cost of parts for replacing a control valve or control module can range from $100 to $500, while labor costs can add an additional $100 to $300. Overall, the total repair cost for this issue can range from $200 to $800. It's important to note that these are rough estimates, and actual costs may vary based on the vehicle make and model, as well as the labor rates at the auto repair shop. It's recommended to consult with a professional mechanic for a more accurate cost estimate.

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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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