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 having trouble reading the level of a special fluid that helps clean the exhaust. It's like when your video game controller can't tell how much battery is left.
The P203C code is triggered when the Engine Control Module (ECM) detects a low voltage signal from the reductant level sensor, indicating a possible issue with the sensor or its circuit.
The reductant level sensor is part of the Selective Catalytic Reduction (SCR) system, which reduces nitrogen oxide emissions in diesel engines. The sensor monitors the level of diesel exhaust fluid (DEF) in the tank. A low circuit signal suggests a problem with the sensor's ability to accurately report the DEF level to the ECM.
• Check Engine Light illuminated
• Possible reduction in engine performance
• SCR system warning light on
• Faulty reductant level sensor
• Wiring issues or poor electrical connections
• DEF tank is empty or low
Reductant: A substance used to reduce emissions in the exhaust system, such as diesel exhaust fluid (DEF).
SCR: Selective Catalytic Reduction, a system used to reduce nitrogen oxide emissions in diesel engines.
• Check the DEF level in the tank
• Inspect the wiring and connections to the reductant level sensor
• Test the reductant level sensor for proper operation
• Refill the DEF tank if low or empty
• Repair or replace damaged wiring or connectors
• Replace the reductant level sensor if faulty
• OBD-II scanner
• Multimeter
• Basic hand tools
$100 - $500
Moderate
• Ford F-250
• Chevrolet Silverado 2500
• Ram 2500
• Regularly check and refill DEF levels
• Inspect sensor wiring during routine maintenance
• Use high-quality DEF fluid
Sensor Issue
• Do not ignore the warning light; address the issue promptly.
• Keep DEF levels topped up to avoid triggering the code.
Check with your vehicle manufacturer for warranty coverage on emissions-related components.
This code is commonly associated with diesel engines equipped with SCR systems, introduced to meet stricter emissions standards.
Moderate – While not immediately critical, it should be addressed soon to avoid potential engine performance issues.
Ignoring emissions-related codes can lead to increased emissions and may violate environmental regulations.
• Engine running
• DEF tank level low
The reductant level sensor is typically located in or near the DEF tank.
Q: Can I drive with a P203C code?
A: It is possible to drive with this code, but it is advisable to address it soon to ensure proper vehicle performance and emissions compliance.
Q: Will a P203C code affect my fuel efficiency?
A: While it may not directly affect fuel efficiency, unresolved issues with the SCR system can lead to other performance problems.
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