P2042 Fault Code

Reductant Temperature Sensor Circuit

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

The P2042 fault code refers to an issue with the reductant temperature sensor circuit, which is responsible for measuring the temperature of the diesel exhaust fluid (DEF) in diesel engines equipped with selective catalytic reduction (SCR) systems. This code indicates that the Engine Control Module (ECM) has detected a problem in the circuit of the reductant temperature sensor.

• The reductant temperature sensor plays a crucial role in ensuring that the SCR system operates efficiently and effectively.
• A malfunction in this circuit can lead to improper DEF injection, potentially causing increased emissions or engine performance issues.

What are the symptoms of the P2042 code?

When the P2042 fault code is triggered, you may notice various symptoms, including:

• An illuminated check engine light on the dashboard.
• Reduced engine performance or power, especially during acceleration.
• Increased emissions due to improper DEF injection.
• Potential engine failsafe mode activation, which limits engine operation to prevent damage.

What causes the P2042 code?

Several factors can contribute to the P2042 fault code:

• A defective reductant temperature sensor may not provide accurate readings.
• Damaged wiring or connectors in the sensor circuit can result in poor electrical connectivity.
• Short circuits or open circuits in the sensor circuit can disrupt normal operation.
• The presence of contaminants or moisture in the sensor can affect its functionality.

How to fix P2042?

To resolve the P2042 fault code, consider the following steps:

• Begin with a thorough diagnostic to confirm the fault code and identify any other related codes.
• Inspect the wiring and connectors for any signs of damage, corrosion, or loose connections.
• Test the functionality of the reductant temperature sensor using a multimeter;
• Replace the sensor if it is found to be defective or malfunctioning.
• Once repairs are completed, clear the fault codes and perform a test drive to ensure the issue is resolved.