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 thinks there's a problem with the sensor that checks the pressure of a special fluid used to clean the exhaust. It's like when a video game controller isn't working right, and you can't play the game properly.
The P204B code indicates that the reductant pressure sensor, which monitors the pressure of the diesel exhaust fluid (DEF), is not operating within the expected range or performance levels.
The reductant pressure sensor is part of the Selective Catalytic Reduction (SCR) system in diesel engines. It measures the pressure of the DEF, which is injected into the exhaust stream to reduce emissions. If the sensor's readings are outside the expected range, the engine control module (ECM) triggers the P204B code.
• Check Engine Light illuminated
• Reduced engine performance
• Possible increase in emissions
• Faulty reductant pressure sensor
• Wiring issues or poor electrical connections
• Defective reductant pump
Reductant: A substance used to reduce emissions, often referring to diesel exhaust fluid.
SCR: Selective Catalytic Reduction, a system used to reduce nitrogen oxide 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 pressure sensor for proper operation.
• Replace the reductant pressure sensor if faulty.
• Repair or replace damaged wiring or connectors.
• Replace the reductant pump if necessary.
• OBD-II scanner
• Multimeter
• Basic hand tools
$150 - $400
Moderate
• Ford F-Series
• Chevrolet Silverado
• Ram 1500
• Regular maintenance of the SCR system
• Ensure quality DEF is used
• Check wiring connections periodically
Sensor Issue
• Do not ignore the Check Engine Light.
• Have the vehicle inspected by a professional.
• Avoid driving long distances until the issue is resolved.
Check with the vehicle manufacturer for warranty coverage on emissions-related components.
This code has become more common with the increased use of SCR systems in diesel vehicles to meet emissions standards.
Moderate – It should be addressed soon to avoid potential damage to the SCR system and increased emissions.
Driving with a malfunctioning SCR system may violate emissions regulations and could lead to fines.
• Engine at operating temperature
• Vehicle in park or neutral
The reductant pressure sensor is typically located near the DEF tank or along the DEF line.
Q: Can I drive with a P204B code?
A: It's not recommended to drive for extended periods with this code, as it may lead to increased emissions and potential damage to the SCR system.
Q: How do I reset the Check Engine Light after fixing the issue?
A: Use an OBD-II scanner to clear the code after repairs are made. If the issue is resolved, the light should stay off.
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