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 the heater that helps the car's system reduce pollution. The heater isn't working right.
The P20B6 code is triggered when the engine control module (ECM) detects a problem with the performance of the heater circuit in the reductant metering unit, which is part of the vehicle's emission control system.
The reductant metering unit heater is responsible for preventing the diesel exhaust fluid (DEF) from freezing in cold temperatures. The ECM monitors the heater's performance and sets the P20B6 code if it detects an issue with the heater's operation, such as an unexpected voltage or current level.
• Check Engine Light illuminated
• Possible reduction in fuel efficiency
• Potential increased emissions
• Faulty reductant metering unit heater
• Open or shorted wiring in the heater circuit
• Poor electrical connection in the heater circuit
ECM: Engine Control Module
DEF: Diesel Exhaust Fluid
• Use an OBD-II scanner to verify the code.
• Inspect the wiring and connectors of the reductant metering unit heater for damage.
• Test the heater circuit for proper voltage and resistance.
• Repair or replace damaged wiring or connectors.
• Replace the reductant metering unit heater if faulty.
• Clear the code and test drive the vehicle to ensure the issue is resolved.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $500
Moderate
• Ford F-250
• Chevrolet Silverado
• Dodge Ram 2500
• Regularly inspect and maintain the emission control system.
• Ensure proper DEF levels and quality.
• Perform routine vehicle diagnostics.
Emission Control System Issue
• Address the issue promptly to avoid increased emissions.
• Consult a professional mechanic if unsure about repairs.
Check with the vehicle manufacturer for warranty coverage on emission control components.
This code has become more common with the increased use of DEF systems in diesel engines.
Moderate – Addressing this issue will help maintain fuel efficiency and reduce emissions.
Driving with increased emissions may violate environmental regulations.
• Engine at operating temperature
• Ambient temperature below freezing
The reductant metering unit heater is typically located near the DEF tank or along the DEF delivery line.
Q: Can I drive with a P20B6 code?
A: It's possible to drive, but it's recommended to fix the issue to avoid increased emissions and potential fuel efficiency loss.
Q: What happens if I ignore this code?
A: Ignoring the code can lead to increased emissions, reduced fuel efficiency, and potential damage to the emission control system.
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