If you have a Nissan and it is giving a P0456 error code, the onboard computer (ECM) is seeing a problem with the EVAP system.
The EVAP system is a part of emissions that send gas vapors from the gas tank to the engine to be burnt away.
The official definition of a Nissan P0456 error is a “Small Leak Detected in the EVAP System.”
Often related codes also are given, such as a P0448 (Vent Control Valve) and P0442 (Evap Small Leak)
What is a P0456 Nissan Code?
A Nissan P0456 OBDII error code is a Small Leak Detected in the EVAP System.
The EVAP system is built into modern cars to stop gas vapors from leaking into the atmosphere.
This helps reduce emissions and gives vehicles better efficiency.
When a leak happens in the system, or it has a failed component, a P0456 error code will be given.
3 Causes and Fixes Nissan P0456 Code
- Gas Cap
- Purge Valve
- Leak In EVAP System
If a gas cap is not tightened correctly or is not sealing, it will cause a small leak.
Check the gas cap is on tight and examine if the rubber seal is not broken.
Grime or other debris can also sometimes stop a gas cap from making a good seal.
Some mechanics will buy a new gas cap to rule it out as a possible cause.
If you do, buy a new gas cap, be sure it is made for your Nisan make and model, as there can be differences.
A purge valve solenoid opens and closes to vent the gas vapors back into the engine to be burnt off.
It will open when a car is running and close when a vehicle is shut off.
It can fail and cause EVAP errors such as a P0456 code.
Often when a purge valve solenoid fails, it is stuck open all the time or stuck closed all the time.
Most Nissan’s will have the solenoid located under the vehicle and have latches that snap it into place.
Replacing a vent solenoid falls in the DIY category but be sure to call a professional if in doubt.
A new solenoid can be bought at an auto parts store or online at Amazon or eBay.
There may be a leak in the EVAP system that is hard to find.
Hard-to-find leaks are often found with a smoke machine.
A smoke machine will feed smoke into the EAVP system and will come out where the leak is located, making it easy to spot.
Summary
If your Nissan engine light comes on and after an OBDII scan tool gives a P0456, it is pointing to an EVAP system problem.
Most EVAP system problems are easy to fix with either the gas cap bad or a bad vent solenoid.
Although usually an easy fix, sometimes it can be hard to locate a very small leak.
If you have a smoke machine, it will be easy to locate the leak, but often most DIY individuals do not have one.
While a smoke machine can be bought, it is often best to take your vehicle to a mechanic for hard-to-find leaks.
Have you had an issue with a Nissan and a P0456 error code? Let us know your thoughts below.