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 is getting a signal that the pressure of a special fluid used to clean the exhaust is too low.
The P204C code indicates that the reductant pressure sensor is reading a pressure that is lower than expected by the engine control module (ECM).
The reductant pressure sensor is part of the diesel exhaust fluid (DEF) system, which helps reduce emissions. This sensor monitors the pressure of the DEF fluid in the system. If the sensor reads a pressure lower than the specified range, the ECM triggers the P204C code.
• Check Engine Light is on
• Reduced engine performance
• Increased emissions
• Possible DEF warning light
• Faulty reductant pressure sensor
• Wiring issues (damaged wires or poor connections)
• Low DEF fluid level
• Defective DEF pump
DEF: Diesel Exhaust Fluid, a liquid used to reduce emissions in diesel engines.
ECM: Engine Control Module, the computer that manages engine functions.
• Check DEF fluid level and refill if necessary
• Inspect wiring and connectors for damage or corrosion
• Test the reductant pressure sensor for proper operation
• Check the DEF pump functionality
• Replace the reductant pressure sensor if faulty
• Repair or replace damaged wiring or connectors
• Refill DEF fluid if low
• Replace the DEF pump if defective
• OBD-II scanner
• Multimeter
• Wrench set
$150 - $500
Moderate
• Ford F-250
• Chevrolet Silverado
• Ram 2500
• Regularly check and maintain DEF fluid levels
• Perform routine inspections of wiring and connectors
• Ensure the DEF system is serviced according to manufacturer recommendations
Sensor Issue
• Do not ignore the Check Engine Light; have the vehicle inspected promptly
• Keep a spare bottle of DEF fluid in the vehicle for emergencies
Repairs may be covered under the vehicle's emissions warranty if applicable.
The P204C code has become more common with the increased use of DEF systems in diesel vehicles to meet stricter emissions standards.
Moderate – Addressing this issue is important to maintain vehicle performance and emissions compliance.
Ignoring emissions-related codes can lead to failing emissions tests and potential fines.
• Vehicle at operating temperature
• DEF system active
The reductant pressure sensor is typically located near the DEF tank or along the DEF fluid lines.
Q: Can I drive with a P204C code?
A: While the vehicle may still be drivable, it is not recommended to ignore this code as it can affect emissions and performance.
Q: How often should I check DEF fluid levels?
A: Check DEF fluid levels regularly, especially before long trips, and refill as needed.
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