The owner of a 2018 Toyota Corolla, L4-1.8L, with a mileage of 368,473, came into a repair shop with an illuminated malfunction indicator light (MIL) on but claimed the car ran fine.
Case details
When the technician connected a scan tool, he found diagnostic trouble code (DTC) P0441 - Evaporative Emission Control System Incorrect Purge Flow.
He replaced the purge solenoid valve and the leak detection pump, but the DTC came back almost immediately. Next, he smoke-tested the evaporative system and found a small leak coming from the leak detection pump even when it was commanded closed. He then called ALLDATA Tech-Assist
The Tech-Assist consultant advised that a small leak in the leak detection pump is normal since there is a calibration port in it. An effective testing method is to physically block the pump port and then check for leaks.
He also advised the technician to check to see if the canister was broken up or saturated, especially considering the vehicle's high mileage.
The technician checked the canister first and found it was very heavy. It was saturated with water.
Confirmed repair
The technician replaced the complete canister assembly, cleared the DTC, and performed a specific "drive cycle" on the test drive to set evaporative monitors to complete status. The MIL stayed off and there were no further issues.
