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 there's a problem with the part of the car that helps control pollution. It's like a valve that lets air in, but it's not working right.
The P20A9 code is triggered when the Engine Control Module (ECM) detects a high voltage condition in the reductant injection air pressure control valve circuit.
The reductant injection air pressure control valve is part of the Selective Catalytic Reduction (SCR) system, which reduces emissions by injecting a urea-based solution into the exhaust. The valve controls the air pressure needed for proper injection. A 'circuit high' condition indicates that the voltage in the control circuit is higher than expected, possibly due to a short circuit or faulty component.
• Check Engine Light is on
• Reduced engine performance
• Increased emissions
• Faulty reductant injection air pressure control valve
• Wiring issues such as short circuits or damaged wires
• Faulty Engine Control Module (ECM)
ECM: Engine Control Module, the computer that controls the engine's functions.
SCR: Selective Catalytic Reduction, a system that reduces emissions in diesel engines.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connections to the control valve for damage.
• Test the reductant injection air pressure control valve for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the reductant injection air pressure control valve if faulty.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Ford F-250
• Chevrolet Silverado
• Ram 2500
• Regularly inspect and maintain the SCR system.
• Ensure proper urea solution levels are maintained.
• Address any Check Engine Light issues promptly.
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional if unsure.
• Regular maintenance can prevent such issues.
Check with the vehicle manufacturer for specific warranty coverage related to emissions systems.
This code has become more common with the increased use of SCR systems in diesel engines to meet emissions regulations.
Moderate – Addressing this issue can prevent increased emissions and potential damage to the SCR system.
Driving with a malfunctioning emissions system may violate local emissions laws and contribute to pollution.
• Engine running
• Vehicle at operating temperature
The reductant injection air pressure control valve is typically located near the SCR system, which is part of the exhaust system.
Q: Can I drive with a P20A9 code?
A: It's not recommended as it can lead to increased emissions and potential damage to the emissions system.
Q: How can I prevent this code from appearing?
A: Regular maintenance and inspections of the emissions system can help prevent this issue.
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