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 sensor that checks the temperature of a special fluid used to clean the car's exhaust. Sometimes it works, and sometimes it doesn't.
The P20B0 code is triggered when the Engine Control Module (ECM) detects an intermittent or erratic signal from the temperature sensor in the reductant metering unit, which is part of the vehicle's emissions control system.
The reductant metering unit temperature sensor monitors the temperature of the diesel exhaust fluid (DEF) used in the Selective Catalytic Reduction (SCR) system to reduce emissions. An intermittent or erratic signal may indicate wiring issues, sensor malfunction, or connectivity problems.
• Check Engine Light is on
• Poor fuel efficiency
• Increased emissions
• Faulty temperature sensor
• Wiring issues or poor connections
• Faulty ECM
ECM: Engine Control Module
DEF: Diesel Exhaust Fluid
SCR: Selective Catalytic Reduction
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the temperature sensor for proper operation.
• Repair or replace damaged wiring or connectors.
• Replace the faulty temperature sensor.
• Reprogram or replace the ECM if necessary.
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $400
Moderate
• Ford F-250
• Chevrolet Silverado 2500
• Ram 2500
• Regular maintenance checks
• Ensure proper fluid levels
• Inspect wiring periodically
Sensor Issue
• Get the vehicle checked by a professional mechanic.
• Avoid ignoring the Check Engine Light.
Check with the vehicle manufacturer for warranty coverage on emissions-related components.
This code has been associated with emissions control systems in diesel vehicles since the implementation of stricter emissions standards.
Moderate – Addressing this issue is important to maintain emissions compliance and vehicle efficiency.
Driving with emissions-related issues can lead to fines and increased pollution. Address promptly.
• Engine running
• Vehicle at operating temperature
The reductant metering unit is typically located near the DEF tank or SCR catalyst.
Q: What is a reductant metering unit?
A: It's a component in diesel vehicles that controls the amount of DEF injected into the exhaust system.
Q: Can I drive with a P20B0 code?
A: It's not recommended as it may lead to increased emissions and reduced fuel efficiency.
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Universal · Digital multimeter
A solid entry-level multimeter for voltage, continuity, resistance, and basic electrical troubleshooting.
Helpful for checking voltage drops, grounds, and basic circuit health when modules are not communicating.
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Universal · Wire connectors and repair kit
Useful when diagnosis points toward damaged wiring, corroded terminals, or connector repairs.
Useful if diagnosis points toward damaged connectors, wiring, or terminal repairs.
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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.