// Leak detection

Smoke machines for cars: find the leak instead of guessing

A lean code, a whistle under load or an EVAP light can take hours of hunting. A smoke machine fills the system with visible vapour and the leak shows itself, usually in minutes.

How it works

The machine heats a smoke fluid into a dense vapour and pushes it at low pressure into a system you've sealed off: the intake, the vacuum lines, the EVAP system or the exhaust. Wherever there's a crack, a loose clamp or a failed seal, smoke comes out. You look, you find it.

The engine stays off. The machine provides the pressure, so you can take your time and check every corner with a light.

What it finds

SystemTypical symptomsCommon codes
Intake and vacuumRough idle, hesitation, whistlingP0171, P0174 (running lean)
EVAPCheck engine light, fuel smellP0442, P0455, P0456 (EVAP leak)
Boost (turbo cars)Underboost, loss of power, hissingUnderboost and lean codes vary by car
ExhaustTicking, exhaust smellCan affect oxygen sensor readings

A code tells you the engine noticed something wrong. Smoke tells you where. Read the code first with a code reader, then use smoke to find the physical cause.

Running a smoke test

  1. Engine off and cool enough to work around.
  2. Seal the system. For the intake, block it after the air filter and introduce smoke through a vacuum port or the intake tube, using the supplied adapters or cone.
  3. Connect power, usually clips to the car battery, and let the machine fill the system.
  4. Look for smoke with a bright light: hoses, gaskets, clamps, the throttle body, the PCV system.
  5. Fix, then re-test to confirm the leak is gone.
EVAP safety. EVAP systems hold fuel vapour. Follow the machine's own EVAP procedure, keep the engine off, work in a ventilated space, and keep sparks and flames away. Use only the smoke fluid the machine is designed for.

Why not carb cleaner or a spray bottle?

Spraying flammable cleaner around a running, hot engine and listening for an idle change is a fire risk, and it only finds leaks the engine happens to be pulling in at that moment. Soapy water only works where you can reach. Smoke finds leaks with the engine off, including behind and under parts you can't see directly.

The machine in our shop

The Podofo EVAP Smoke Leak Detector is a 12 V unit with a pressure gauge that runs from the car battery. It covers intake, vacuum, EVAP and exhaust testing, which is what most DIY and workshop leak hunts need.

Questions people actually ask

Will smoke damage sensors or the engine?
Used as intended, with the engine off and the fluid the machine is designed for, smoke testing is a standard workshop procedure. Follow the machine's instructions for where to introduce the smoke.
Can it find a boost leak?
Yes. Seal the intake before the turbo and after the throttle as the instructions describe, fill the system with smoke, and look along the intercooler pipes, couplers and clamps.
Can I use it for cabin wind or water leaks?
Some people use smoke to trace air leaks into the cabin, but the main job of an automotive smoke machine is engine-bay leaks: intake, vacuum, EVAP and exhaust.
How long does a test take?
Setting up takes a few minutes. The leak often shows within a minute or two of the system filling.

The machine this page is about.

Podofo EVAP Smoke Leak Detector, 12 V with pressure gauge. €109, shipped free, 2-year warranty.

See it in the shop → Read the code first