Maintenance Tips, Tricks And Hacks For Your Vehicle

P0456 OBD-II Evaporative Emissions System Small Leak Detected Trouble Code




The P0456 is an OBD-II generic trouble code that stands for Evaporative Emissions System Small Leak Detected. This code is triggered when the vehicle’s computer detects a small leak in the EVAP.

In this article, I will be talking about P0456, its symptoms, causes, and how to fix it.

What Does The P0456 Trouble Code Mean?

P0456 OBD-II Evaporative Emissions System Small Leak Detected Trouble Code

The P0456 is an OBD-II trouble code which means the vehicle’s computer has detected a very small leak in the evaporative system during the system check. The leak is measured in barometric pressure and a small leak means a drop of .01.

The EVAP system keeps everything sealed and prevents gasoline vapors containing hydrocarbons from escaping into the atmosphere. The gasoline is liquid but it evaporates so quickly. Therefore, the inability of the evaporative system to keep the gasoline vapors inside the vehicle causes a P0456 trouble code.

Which Models Are Affected By The P0456 Trouble Code

MakeAffected By P0456 Code

What Are The Possible Causes of The P0456 Trouble Code?

The P0456 is caused by a small leak in the evaporative system. The EVAP system is completely sealed and as little as a .01 drop in the pressure can trigger the P0456 code. When this happens, the vehicle’s computer reports this to the driver by igniting the check engine light.

Possible causes of the P0456 trouble code include:

  • Missing, loose, or damaged gas cap
  • Leaking EVAP hose
  • Leaking fuel tank
  • Pinhole leak
  • Leaky purge control valve
  • Faulty evaporative vacuum pump

(See also: P0115: Engine Coolant Temperature Sensor 1 Circuit – Meaning, Symptoms, Causes, and How To Fix It )

What Are The Common Symptoms of The P0456 Trouble Code?

Common symptoms of the P0456 trouble code include:

  • Decreased fuel economy
  • Check engine light
  • Fuel smell inside the cabin
  • Could possibly fail an emissions test

Is It Safe To Drive With a P0456 Trouble Code

As far as the well-being of the vehicle goes, you can safely drive with a P0456 code. Other than decreased fuel economy, you won’t feel any changes in the way the vehicle drives. However, driving with a P0456 trouble code or an evaporative emissions small leak means that harmful hydrocarbon gases are escaping into the atmosphere.

How To Diagnose The P0456 Trouble Code

To diagnose the P0456 trouble code:

  1. To diagnose the P0456, the vehicle has to be scanned with an OBD2 scanner. The scanner can show you exactly when the fault happened.
  2. Inspect the vapor purge valve system along with the purge valve and the vent valve hose. Look for any loose or damaged connections.
  3. Check the purge valve vent. Look for any blockage that might have been caused by dirt and debris that prevent the valve from completely sealing the vapors.
  4. Perform a smoke leakage test on the fuel vapor system. This will help locate where the vapor leak is.
  5. Test the purge control valve to see if it’s able to hold a vacuum when engaged.

How Much Does It Cost To Repair P0456 Trouble Code

MakeP0456 CodeRepair Cost
ToyotaYes$100 – $500
NissanYes$100 – $500
ChevroletYes$99 – $470
BMWYes$100 – $500
AudiYes$100 – $500
BuickYes$70 – $300
MercedesYes$100 – $600
GMCYes$100 – $500
SuzukiYes$100 – $500
TataYes$60 – $480
LexusYes$100 – $500
MazdaYes$100 – $500
MitsubishiYes$100 – $500
KiaYes$85 – $485
JeepYes$100 – $500
FiatYes$100 – $500
HondaYes$100 – $500
HyundaiYes$100 – $500
OpelYes$72 – $375
FordYes$100 – $500
FiatYes$80 – $400
PeugeotYes$100 – $500

What Repairs Can Fix The P0456 Trouble Code

Repairs that can fix the P0456 code include:

  1. Replacing the gas cap
  2. Cleaning the gas filler neck with WD40 and a clean towel
  3. Replacing a faulty canister purge valve
  4. Replacing a leaky EVAP hose
  5. Repairing or replacing a leaky fuel tank
  6. Replacing a faulty evaporative vacuum pump

How To Fix The P0456 Trouble Code

Here is how to fix the P0456 code:

  • Replace the damaged gas cap
  • Replace or clean the clogged purge vent valve
  • Replace the leaking purge valve
  • Replace the leaky fuel tank
  • Clean the gas filler neck
  • Replace the faulty EVAP vacuum pump

In Conclusion

The P0456 trouble code stands for Evaporative Emissions System Small Leak Detected. Although the car is driveable with this code, the ride will not be pleasant. The vehicle will start to burn more gas than needed in order to compensate for the lost air.



Vide Polowenski, Senior Mechanic

The information in this article is current and up-to-date in accordance with the latest mechanic SOPs.

Please take the time to leave a comment if this article has helped you in any way, you need additional help, or you have a suggestion.

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