LOW
System: EVAP Emissions System
SAE J2012 Standard
P0456: Evaporative Emission System Leak Detected (Very Small Leak)
The ECM detects a micro-leak equivalent to a pinhole of just 0.020 inch (0.5 mm) in the sealed fuel vapor system.
Driveability & Safety Advisory
Safe to drive. No performance impact.
Official Manufacturer TSB Advisories
Chrysler 25-001-18
Target: 2011–2018 Jeep Grand Cherokee / Ram 1500
Factory Condition: Natural Vacuum Leak Detection (ESIM / NVLD) switch diaphragm stiffens in cold weather.
OEM Service Remedy: Replace ESIM switch on charcoal canister (Part #4861962AA).
Physical Component Location & Service Access
EVAP canister switch on fuel tank or canister.
Electrical Specifications & Live PID Benchmarks
Scan Tool Live Data Targets
ESIM Switch State:
Open / Closed switch verification
Digital Multimeter (DMM) Specs
Switch Continuity:
0.0 Ohms when closed
Documented Model-Specific Case Studies
2014–2019 Jeep Cherokee
Root Cause: Faulty ESIM switch.
Verified Fix: Replace ESIM detector switch.
Technician Inspection & Testing Workflow
1
Clean gas cap rubber seal with clean cloth.
2
Smoke test system with 0.020-inch test gauge.
3
Inspect ESIM switch.
Cost Breakdown
DIY Replacement Parts:
$20 – $55
Independent Repair Shop (Parts + Labor):
$150 – $320
Standard Diagnostic Time:
1.0 – 2.0 Flat-Rate Hours
Tools & Parts Matrix
Recommended Parts:
Gas cap, ESIM switch
Required Test Tools:
Smoke machine, Scan tool
Diagnostic Questions & Answers
How small is a P0456 leak?
0.020 inches—about the thickness of a sewing pin!