P2039 Fault Code

Reductant Injection Air Pressure Sensor Circuit Low

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

The P2039 fault code refers to an issue with the Reductant Injection Air Pressure Sensor Circuit, indicating that the circuit is detecting a lower than expected air pressure. This sensor is crucial for the proper functioning of the selective catalytic reduction (SCR) system, which helps reduce emissions in diesel engines. When the air pressure readings fall below the preset parameters, fuel efficiency and emission controls may be compromised.

What are the symptoms of the P2039 code?

Drivers may notice several symptoms when this error code is present, such as:

• Reduced engine performance
• Increased emissions
• Illuminated check engine light
• Potential decrease in fuel efficiency
• Possible limp mode activation, limiting vehicle speed and power.

What causes the P2039 code?

Common causes for this fault code include:

• Faulty reductant injection air pressure sensor
• Wiring issues or short circuits in the pressure sensor circuit
• Vacuum leaks in the system
• Malfunctioning SCR system components
• Corrosion or damage to connectors and terminals associated with the sensor.

How to fix P2039?

To resolve a P2039 fault code, the following steps should be taken:

1. Inspect the reductant injection air pressure sensor for damage or corrosion.
2. Test the sensor's wiring and connectors for any signs of wear or shorts.
3. Replace the sensor if it is found to be faulty.
4. Check for vacuum leaks within the system and repair as necessary.
5. Clear the fault code and perform a test drive to ensure the issue is resolved.