Diagnosing P0441 EVAP Incorrect Purge Flow on a 2019 Ram 1500

Understanding the P0441 EVAP Code

• 💡 The video addresses a common P0441 code on a 2019 Hemi Dodge Ram, defined as "EVAP system incorrect purge flow."
• 🎯 This code typically indicates that the Powertrain Control Module (PCM) is detecting unwanted purge flow within the evaporative emission control system.

Diagnostic Approach for EVAP Systems

• 🔍 The diagnostic process begins by examining live data, focusing on parameters related to the EVAP system.
• 🔑 Chrysler's EVAP system uses a purge valve and an Emissions System Integrity Monitor (EIM) switch, but notably lacks a separate vent valve found in other manufacturers' systems.
• ⚠️ Key initial checks involve verifying the EIM switch status and the fuel tank pressure sensor's voltage when the engine is off and the key is on.

Fuel Tank Pressure Sensor Diagnosis

• 📊 For a 2019 Dodge Ram, with the key on and engine off, the fuel tank pressure should ideally read near zero inches of water, and the fuel tank pressure sensor should output approximately 2.5 volts.
• ⚡ In this specific case, the initial readings were abnormal, indicating a potential issue with the fuel tank pressure sensor or its wiring.
• 🛠️ The technician then physically inspected the sensor, located near the fuel filler neck, and confirmed the connector was not corroded.
• 🧪 A three-wire bypass test was performed on the sensor to check wiring integrity and confirm the sensor's functionality, revealing that the sensor itself was faulty.

Replacing the Fuel Tank Pressure Sensor

• 📍 The fuel tank pressure sensor is a critical component that can fail, leading to incorrect readings and setting EVAP codes.
• ⚙️ The replacement process involves accessing the sensor above the fuel tank, releasing a locking mechanism, and installing the new part.
• ✅ After installation, key-on engine-off voltage readings were within the expected range (around 2.66 volts), and subsequent tests confirmed the system was functioning correctly.

Common EVAP Issues and Lessons Learned

• ⚠️ While the fuel tank pressure sensor was the culprit in this instance, the technician notes that a stuck-open purge valve can also cause similar symptoms.
• 🧠 The importance of using scan tool data, service information, and understanding the specific EVAP system of the vehicle is emphasized for accurate diagnosis.
• 💡 Even common codes can have varied causes, making a systematic diagnostic approach essential.