<ul> <li><b>Engine Light ON (or Service Engine Soon Warning Light)</b>: <b>Engine Light ON</b> indicates a problem with the vehicle's emissions system. <ul><li>Potential causes: Faulty EVAP purge pump, wiring issues, or a malfunctioning control module.</li></ul></li> <li><b>Possible Fuel Odor</b>: <b>Possible Fuel Odor</b> may be noticed due to the EVAP system's inability to properly purge fuel vapors. <ul><li>Potential causes: Faulty EVAP purge pump or leaks in the EVAP system.</li></ul></li> <li><b>Decreased Fuel Efficiency</b>: <b>Decreased Fuel Efficiency</b> can occur if the EVAP system is not functioning correctly, leading to improper fuel vapor management. <ul><li>Potential causes: Malfunctioning EVAP purge pump or related components.</li></ul></li> </ul>

<ul><li>The evaporative emission purge pump may be faulty, leading to a loss of communication.</li><li>An open or shorted harness in the evaporative emission purge pump can disrupt the signal.</li><li>Poor electrical connections in the evaporative emission purge pump circuit can cause intermittent communication issues.</li><li>A malfunctioning Engine Control Module (ECM) can fail to communicate with the evaporative emission purge pump.</li></ul>

<ul> <li><b>Initial Scan</b>: Use an OBD-II scanner to confirm the presence of DTC U111E and check for any other related codes.</li> <li><b>Visual Inspection</b>: Inspect the EVAP purge pump and its wiring for any visible damage, corrosion, or loose connections.</li> <li><b>Check Power Supply</b>: Verify that the EVAP purge pump is receiving the correct voltage by using a multimeter to check the power supply at the pump connector.</li> <li><b>Test Ground Connection</b>: Ensure the ground connection for the EVAP purge pump is secure and has low resistance. Use a multimeter to measure the resistance between the ground terminal and a known good ground.</li> <li><b>Inspect CAN Bus</b>: Check the Controller Area Network (CAN) bus lines for continuity and proper termination. Look for any signs of damage or shorts in the wiring.</li> <li><b>Module Communication Test</b>: Use a scan tool to perform a communication test between the Engine Control Module (ECM) and the EVAP purge pump to ensure proper data exchange.</li> <li><b>Check for Software Updates</b>: Verify if there are any software updates or Technical Service Bulletins (TSBs) related to the EVAP system that may address communication issues.</li> <li><b>Component Replacement</b>: If all tests indicate a faulty EVAP purge pump, replace the pump and clear the DTC code. Re-test the system to ensure the issue is resolved.</li></ul>

<p>The DTC code U111E indicates a <b>Lost Communication with EVAP Purge Pump</b>. This is a critical issue as it affects the vehicle's ability to manage fuel vapors, potentially leading to increased emissions and fuel inefficiency.</p><ul><li>Immediate inspection of the EVAP system and communication lines is necessary.</li><li>Failure to address this promptly can result in failed emissions tests and potential engine performance issues.</li></ul>