What Happens
The shop seals the system, fills it with smoke at low pressure and looks for where it comes out. A hose split, a loose clamp or a filler neck seal shows up as a thin line of smoke. FCA tells techs to leave the original cap on during the test, because a test adapter can hide a cap leak (FCA bulletin).
What It Costs
| Price | Source | What It Covers |
|---|---|---|
| $61 to $90 | RepairPal | national average estimate, labor only |
| $169.99 to $184.99 | YourMechanic | mobile mechanic diagnostic fee by make |
| $150 | Supercanic (internal shop records) | single invoice, 2005 Mercedes E55 |
Our own smoke test row is from a job where the leak was on the intake, not the EVAP side. It is the same machine and the same hourly rate. Read a smoke test we ran on a 2005 E55.
By Anthony Limpert, co-founder of Supercanic in San Jacinto, California, a shop with ASE certified mechanics. Updated November 12, 2026.
Author Source EEAT Authors · Anthony's Author Page
Sources For This Page
- TSB 01-002/18, Determining Evaporative System Leak Location for P0441, P0442, P0455, P0456 (January 30, 2018), Mazda North American Operations, read 2026-11-12
- STAR Online case S2025000004, P0456 or P0455 (April 28, 2020), FCA US LLC, read 2026-11-12
- Emission System Diagnosis and Testing Cost Estimate, RepairPal, read 2026-11-12
- P0442 Trouble Code Help and Fix, YourMechanic, read 2026-11-12
- Supercanic shop invoices, Supercanic (internal shop records), read 2026-11-12