Vehicle: 2007 Dodge Ram 1500, 2WD, V8-4.7L, VIN N, Automatic Transmission/Transaxle

Mileage: 149,093 miles

Problem: A Dodge Ram owner brought his truck to the shop because the malfunction indicator light (MIL) was on. He had already taken it to another shop, which found evaporative system diagnostic trouble code P0441 -- Evaporative Emission Control System Incorrect Purge Flow. They replaced the Evaporative System Integrity Monitor (ESIM) with a factory part, but the MIL came back on almost immediately.

Case Details: The technician connected a scan tool and found DTCs P0440 - Evaporative Emission Control System Malfunction and P0456 - Evaporative Emission Control System Leak Detected (Very Small Leak).

He smoke-tested the evaporative system but found no leaks. The OEM evaporative purge valve that he installed two years ago still tested good. Next, he assessed the ESIM switch by checking for voltage while blocking the vent hose and applying vacuum to the canister. The voltage never dropped to zero, as per testing specifications, or never switched to the “closed” position on the scan tool. NOTE: Even with 1hg vacuum applied, the voltage should drop to zero, and the switch status needs to indicate the switch is closed.

A quick call to ALLDATA Tech-Assist provided a quick, simple answer. The consultant suggested checking the ESIM installation. Apparently, the ESM switch can be installed in four separate positions. Only one is correct. The electrical connector must be in the 3:00 position (see images) or the switch will not operate correctly. The switch was installed incorrectly.

Confirmed Repair: The technician installed the ESIM switch properly and cleared all DTCs. The ESIM switch voltage began dropping to zero volts, and the switch status showed closed. After taking the truck on a test drive and running an evaporative system drive cycle, the DTCs did not return. Easy fix!