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 the car's computer has detected a problem with the heater that helps keep the fluid used to clean up exhaust gases warm. It's like a little heater that isn't working right.
The P20C5 code indicates that there is an issue with the electrical circuit for the reductant heater, which is responsible for warming the diesel exhaust fluid (DEF) to prevent it from freezing.
The reductant heater is part of the Selective Catalytic Reduction (SCR) system in diesel engines. It ensures the DEF remains fluid in cold temperatures. An open circuit or control issue in this heater can lead to improper DEF flow and SCR system performance.
• Check Engine Light (CEL) is on
• Reduced engine performance
• Increased emissions
• SCR system warning light
• Faulty reductant heater
• Open or shorted wiring in the heater circuit
• Blown fuse
• Faulty control module
Reductant: A substance used to reduce emissions, commonly DEF in diesel engines.
SCR: Selective Catalytic Reduction, a system used to reduce NOx emissions in diesel engines.
• Use an OBD-II scanner to confirm the code
• Inspect the wiring and connectors for damage
• Check the fuse related to the reductant heater
• Test the reductant heater for proper resistance
• Replace the faulty reductant heater
• Repair or replace damaged wiring or connectors
• Replace blown fuse
• Reprogram or replace the control module if necessary
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Ford F-Series
• Chevrolet Silverado
• Ram 2500
• Regularly inspect and maintain the SCR system
• Ensure proper DEF quality and levels
• Address wiring issues promptly
Sensor Issue
• Do not ignore the Check Engine Light
• Have the vehicle inspected by a professional
• Avoid driving in extremely cold conditions until repaired
Check with your vehicle manufacturer for specific warranty coverage on emission-related components.
This code has become more common with the increased use of SCR systems in diesel vehicles to meet emission standards.
Moderate – While it may not cause immediate damage, it can affect emissions and engine performance.
Driving with a malfunctioning emission system may violate local emissions laws and regulations.
• Ensure the engine is cold
• Test in a controlled environment to prevent accidental damage
The reductant heater is typically located near the DEF tank or within the DEF delivery system.
Q: Can I drive with a P20C5 code?
A: It's not recommended as it can lead to increased emissions and reduced engine performance.
Q: How can I prevent this code from appearing?
A: Regular maintenance and ensuring the DEF system is functioning properly can help prevent this code.
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