Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means there's a problem with a sensor that checks the temperature of a special fluid used to make the car's exhaust cleaner. It's like a thermometer for the car's cleaning system, and it's not working right.
The P20AE code indicates that the reductant metering unit temperature sensor is reporting a lower than expected voltage, suggesting a potential issue with the sensor or its circuit.
The reductant metering unit temperature sensor is part of the Selective Catalytic Reduction (SCR) system, which reduces emissions by injecting a urea-based fluid into the exhaust. The sensor monitors the temperature to ensure optimal fluid injection. A low circuit reading suggests a malfunction in the sensor or wiring, leading to incorrect temperature readings.
• Check Engine Light (CEL) illuminated
• Possible reduction in engine performance
• Increased emissions
• Faulty reductant metering unit temperature sensor
• Wiring issues such as shorts or open circuits
• Connector corrosion or damage
SCR: Selective Catalytic Reduction, a system that reduces emissions in diesel engines.
Reductant: A fluid, often urea-based, used in the SCR system to reduce emissions.
• Perform a visual inspection of the sensor and wiring.
• Use a multimeter to check the sensor's voltage and resistance.
• Inspect and clean the sensor's connector.
• Replace the reductant metering unit temperature sensor if faulty.
• Repair or replace damaged wiring or connectors.
• Clear the code and test drive to ensure the issue is resolved.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Ford F-250
• Chevrolet Silverado 2500
• Ram 2500
• Regularly inspect and maintain the SCR system.
• Ensure proper fluid levels in the reductant tank.
• Keep connectors clean and free of corrosion.
Sensor Issue
• Address the issue promptly to avoid increased emissions.
• Consult a professional if unsure about repairs.
Check the vehicle's emissions warranty, as components related to emissions may be covered.
The P20AE code has become more common with the increased use of SCR systems in diesel engines to meet emissions standards.
Moderate – While the vehicle may still be drivable, addressing the issue is important to maintain emissions compliance and performance.
Driving with a malfunctioning emissions system may violate emissions standards and result in fines.
• Engine running
• System at operating temperature
The reductant metering unit temperature sensor is typically located near the exhaust system, close to the SCR catalyst.
Q: Can I drive with a P20AE code?
A: You can drive, but it's best to fix the issue soon to avoid emissions problems.
Q: What happens if I ignore this code?
A: Ignoring it can lead to increased emissions and potential engine performance issues.
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Specialty · Smoke machine
Helpful for finding EVAP and vacuum leaks that are hard to see with visual inspection alone.
Helpful for tracking down EVAP and vacuum leaks that can trigger emissions faults.
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Specialty · O2 sensor socket
Helpful when the code points toward exhaust or oxygen-sensor work and space is tight.
Useful when the diagnosis points toward oxygen-sensor removal or replacement.
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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.