Evaporative Emission System Leak: Safe To Drive?

An evaporative emission system leak happens due to a defective evaporative emission control system (EVAP). The system keeps the fume in the gas tank contained so it does not get released to the outside atmosphere.

A leak in the EVAP system makes the cabin smell like fuel and increases air pollution. But, the burning question is how safe it is to drive with a leak in the EVAP?

The Causes Of An Evaporative Emission System Leak

The common reasons for the EVAP system to become dysfunctional are:

  • A loose, broken, mismatched, or missing gas cap.
  • Punctured vapor tube or hose.
  • Broken seal in the O-ring. An old O-ring can also create troubles.
  • Other leaks in the vehicle that affect the emissions.
  • There could be extra pressure on the EVAP system when the car is poorly maintained or old.
EVAP leak
EVAP leak increases pollution (Photo Source: fortune)


You will understand that there is something wrong with the system if the check engine light comes on. The most common warning sign for so many problems. It will come on at the time of driving if there is an EVAP leak. You may smell a faint gasoline odor but it won’t be perceptible in all vehicles.

If you have recently filled up the gas tank, check the tank’s cap when the light comes on. A misplaced or loose cap is likely to be the culprit in this case. If the cap is all right, look for a leak in the hose or another part in the EVAP system. The problem could also emerge from a faulty purge valve, a leak detection pump, or an O-ring seal.

An evaporative emission system leak continuously emits vapors from your vehicle, even when you are not driving it. Such unaccounted and uncontrolled emissions are responsible for almost 20% of the pollution caused by automobiles.

If you suspect that the EVAP system is the reason for the check engine light to come on, take a look under the hood before going to a repair shop. Sometimes, it could happen just because of a loose or displaced cap. If that is not the case, you should seek professional help because fixing the EVAP codes could be pretty challenging. Also, it requires an extensive knowledge to find out the source of the leak and determine its gravity.

How Safe Is It To Drive With An EVAP Leak?

Here comes the important question. Safety is a matter of utmost importance when you are driving a vehicle. So, it is critical to know whether you should drive on after suspecting an EVAP leak.

evaporative emission system leak
You can still drive but not too long (Photo Source: iqair)

Luckily, a leak in the EVAP system is not an emergency. You can drive, but going to a mechanic as soon as possible is the right thing to do. Driving with an evaporative emission system leak does not mean that you should drive for hours or continue your road trip. To avoid severe pollution and any possibility of an engine breakdown, you should not drive more than ten to twenty miles.