P203B Fault Code

Reductant Level Sensor Circuit Range/Performance

• What does that mean?
• Symptoms
• Causes
• Solutions

The P203B fault code indicates an issue with the Reductant Level Sensor Circuit, specifically related to its range or performance. This sensor plays a crucial role in measuring the level of diesel exhaust fluid (DEF) in vehicles equipped with selective catalytic reduction (SCR) systems. When the sensor malfunctions, it can lead to inaccurate readings, affecting the vehicle's emissions control and overall engine performance.

• The sensor helps ensure the right amount of DEF is injected into the exhaust system.
• Proper functioning of this sensor is essential for meeting emissions regulations and preventing engine derating.
• Drivers may notice alerts on the dashboard related to DEF levels or performance issues.

What are the symptoms of the P203B code?

When the P203B code is active, you might experience:

• Dashboard warning lights indicating DEF issues.
• Reduced engine power as a protective measure by the vehicle’s computer system.
• Poor fuel economy due to the engine running inefficiently to compensate.
• Potential emissions system warnings or failures, risking compliance with environmental regulations.

What causes the P203B code?

Several factors can contribute to the P203B code being triggered:

• A faulty reductant level sensor due to wear or electrical issues.
• Damaged or corroded wiring and connectors affecting the sensor’s performance.
• Low levels of diesel exhaust fluid (DEF) in the tank, leading to incorrect readings.
• Contaminants or blockages in the sensor housing that impede its function.

How to fix P203B?

To resolve the P203B fault code, consider the following steps:

• Inspect the reductant level sensor and its wiring for damage or corrosion, replacing any faulty components as necessary.
• Check the DEF tank for proper fluid levels, topping it off if low.
• Clean the sensor and its housing to remove any contaminants affecting performance.
• Perform a diagnostic scan to ensure all related systems are functioning correctly after repairs.