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Home >> Jeep >> 2014 >> Wrangler Sahara, Standard Trans >> Repair and Diagnosis >> External Pages >> Different car >> Section 79 (2.4L - DTCS P0443 To P1593) >> Diagnosis And Testing >> P0457-Loose Fuel Cap >> Theory Of Operation

Theory Of Operation

WARNING: This page is about a different car, the 2014 Dodge Journey. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: EVAP System Components
GC0145421Courtesy of CHRYSLER GROUP, LLC
EVAP SYSTEM COMPONENTS
CALLOUT DESCRIPTION
1 Filter
2 ESIM Switch
3 Evaporative Canister
4 Fuel Tank Vent (Check Valve)
5 Control Valve
6 Inlet Check Valve
7 Fuel Tank Pressure Sensor
8 To Purge System
9 Fuel Fill Tube

Fuel level is recorded when the ignition key is turned off and is compared to the fuel level when the ignition key is turned back on. The Powertrain Control Module (PCM) recognizes an increase in fuel level and will fail the Large leak test because the fuel cap is broken or not installed properly. GAS CAP will be displayed to inform the owner that the cap is off of loose.