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 sensor in your car that measures the temperature of a special fluid used to clean the exhaust is reading too high. It's like a thermometer saying it's too hot when it shouldn't be.
The P20AF code indicates that the temperature sensor in the reductant metering unit is reporting a voltage signal that is higher than expected, suggesting a potential issue with the sensor or its circuit.
The reductant metering unit temperature sensor is responsible for monitoring the temperature of the Diesel Exhaust Fluid (DEF) used in the Selective Catalytic Reduction (SCR) system. A high circuit signal could indicate a malfunctioning sensor, wiring issues, or a problem with the control module.
• Check Engine Light illuminated
• Possible reduction in engine performance
• Increased emissions
• Faulty temperature sensor
• Wiring issues or poor connections
• Malfunctioning control module
Reductant: A substance used to reduce emissions, such as DEF.
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 sensor.
• Test the sensor for proper operation.
• Replace the faulty temperature sensor.
• Repair or replace damaged wiring or connectors.
• Reprogram or replace the control module if necessary.
• OBD-II Scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Ford F-250
• Chevrolet Silverado
• Ram 2500
• Regular maintenance of the SCR system
• Ensure quality DEF fluid is used
• Inspect wiring regularly for damage
Sensor Issue
• Have the vehicle inspected by a professional mechanic.
• Avoid driving long distances until the issue is resolved.
Check with your vehicle manufacturer; emissions-related components may have extended warranties.
This code has been known to appear in vehicles with SCR systems, especially those with higher mileage or poor maintenance.
Moderate – Addressing this issue promptly can prevent further emissions-related problems.
Driving with increased emissions may violate environmental regulations.
• Engine at operating temperature
• Vehicle in a safe, stationary position
The reductant metering unit is typically located near the DEF tank or along the exhaust system.
Q: Can I drive with a P20AF code?
A: It's best to have it checked soon, as it may affect emissions and engine performance.
Q: What happens if I ignore this code?
A: Ignoring it could lead to increased emissions and potential damage to the SCR system.
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