Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that a part in the car that helps clean the exhaust is not closing properly. Imagine if you left a door open when it should be closed.
The P20AA code indicates that the reductant injection air pressure control valve is stuck in the open position, which affects the vehicle's ability to properly inject the reductant, such as diesel exhaust fluid (DEF), into the exhaust system.
The reductant injection air pressure control valve is part of the vehicle's selective catalytic reduction (SCR) system. This system reduces emissions by injecting a reductant into the exhaust stream. If the valve is stuck open, it can lead to improper pressure levels and affect the efficiency of the SCR system.
• Check Engine Light is on
• Reduced engine performance
• Increased exhaust emissions
• Faulty reductant injection air pressure control valve
• Electrical issues in the valve circuit
• Contaminated reductant fluid
Reductant: A substance, often diesel exhaust fluid, used in emissions control systems to reduce pollutants.
SCR: Selective Catalytic Reduction, a system used to reduce emissions in diesel engines.
• Use an OBD-II scanner to confirm the code
• Inspect the reductant injection air pressure control valve for damage or blockage
• Check the electrical connections and wiring to the valve
• Replace the faulty valve
• Repair or replace damaged wiring
• Flush and replace contaminated reductant fluid
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $400
Moderate
• Ford F-250
• Chevrolet Silverado
• Ram 2500
• Regularly check and maintain reductant fluid levels
• Ensure quality reductant fluid is used
• Regularly inspect the SCR system components
Emission Control
• Do not ignore the Check Engine Light
• Have the vehicle inspected by a professional
• Avoid driving long distances until the issue is resolved
Check with the vehicle manufacturer for emissions-related warranty coverage.
This code has become more common as emissions standards have tightened and vehicles have adopted more complex emissions control systems.
Moderate – While the vehicle can still be driven, emissions may be higher than allowed, and performance could be affected.
Driving with this issue may lead to failing emissions tests and potential fines in areas with strict emissions regulations.
• Engine at operating temperature
• Vehicle in closed-loop operation
The reductant injection air pressure control valve is typically located near the exhaust system, often close to the catalytic converter or SCR catalyst.
Q: Can I drive my car with a P20AA code?
A: It's possible to drive, but it's not recommended as it may lead to increased emissions and reduced performance.
Q: How do I clear a P20AA code?
A: After repairs, use an OBD-II scanner to clear the code, but ensure the issue is fixed to prevent it from coming back.
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Fitment Required · Vehicle-fitment part
Relevant when catalyst-efficiency or emissions faults persist after proper diagnosis.
Catalyst-efficiency faults sometimes point toward converter problems after proper testing.
Catalytic converters are highly vehicle-specific and should not be purchased by code alone.
View options on AmazonThese parts may be related to this fault category, but a code by itself does not confirm exact fitment or guarantee that replacing a part will solve the problem.