Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This means there's a problem with the part of the car that controls the heater for a special fluid used to clean the exhaust. It's like a switch that isn't working right.
The P20B3 code indicates that the engine control module (ECM) has detected a low voltage condition in the circuit that controls the reductant heater coolant control valve.
The reductant heater coolant control valve is part of the diesel exhaust fluid (DEF) system, which helps reduce emissions. This valve controls the flow of coolant to the heater that warms the DEF. A low circuit condition means the ECM is not receiving the expected voltage signal, possibly due to a wiring issue or a faulty valve.
• Check Engine Light illuminated
• Possible reduction in engine performance
• Increased emissions
• Faulty reductant heater coolant control valve
• Damaged or corroded wiring or connectors
• Blown fuse or relay related to the circuit
Reductant: A fluid used in diesel engines to reduce emissions.
DEF: Diesel Exhaust Fluid, used to reduce emissions in diesel engines.
• Use an OBD-II scanner to confirm the code.
• Inspect the wiring and connectors for damage or corrosion.
• Test the reductant heater coolant control valve for proper operation.
• Replace the faulty reductant heater coolant control valve.
• Repair or replace damaged wiring or connectors.
• Replace any blown fuses or faulty relays.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Ford F-250
• Chevrolet Silverado 2500
• Ram 2500
• Regularly inspect and maintain the DEF system.
• Ensure all wiring and connectors are secure and free of corrosion.
• Use high-quality DEF fluid.
Sensor Issue
• Do not ignore the Check Engine Light; address the issue promptly.
• Have a professional mechanic inspect the DEF system if unsure.
Check with the vehicle manufacturer for specific warranty coverage related to emissions components.
This code has become more common as emissions regulations have tightened, requiring more complex DEF systems.
Moderate – It should be addressed soon to avoid increased emissions and potential damage to the DEF system.
Ignoring emissions-related issues can lead to failing emissions tests and potential fines.
• Engine at operating temperature
• DEF system active
The reductant heater coolant control valve is typically located near the DEF tank or along the DEF fluid lines.
Q: Can I drive with a P20B3 code?
A: You can drive for a short period, but it's best to fix the issue soon to avoid increased emissions.
Q: Is a P20B3 code serious?
A: It's moderately serious as it affects emissions. Address it promptly to avoid further issues.
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