EVAP code P0456

[Mrt858]

2025 Tacoma TRD sport manual transmission bought new 6/1/25. Week 2 of ownership at 400 miles check gas cap message next day CEL (P0456). Took it to the dealership they cleared the code and 2 days later same thing happened. Took it back to dealership and they had it 5 days probably because of the 4th of July holiday they changed the gas cap and 3 days later same thing happened. I bring the truck back to the dealership for the third time this time they had it for 2 weeks and TAS for Toyota was advising them. They changed the canister and purge valve. I get the truck back and 3 days later same problem. I’m at a loss

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[Stringburner]

I wouldn't like that. It doesn't affect driveability, but they should be able to perform the appropriate tests to determine where the leak is instead of slapping parts on it, especially at a brand-specific dealership.

 

[soupy1234]

Probably doesn't apply to a Tacoma but here's a video of the diagnostic process for a similar problem.

 

[inlandsmog]

They are shotgunning parts and not doing the diag. Warranty time doesn't pay well for the tech

 

[Billy K]

Tell them to do a smoke test to find the leak in the system. There is a "tool" to make and pump smoke into the evap system. If there is a small crack in a line or etc. it will find it.

Have you been off roading? Last year on my jeep I had the evap code. I found that a dead and stiff weed stalk had poked a tiny hole in one of the plastic lines back near the gas tank / canister area.

 

[soupy1234]

They are shotgunning parts and not doing the diag. Warranty time doesn't pay well for the tech

They probably get paid more for actually changing parts than they do for diagnostics. Mechanic in the video above also has a video on why you should want to pay for diagnostics and mentions something to that effect.

 

[TacoTuesThey]

Tell them to do a smoke test to find the leak in the system. There is a "tool" to make and pump smoke into the evap system. If there is a small crack in a line or etc. it will find it.

Have you been off roading? Last year on my jeep I had the evap code. I found that a dead and stiff weed stalk had poked a tiny hole in one of the plastic lines back near the gas tank / canister area.

I second that. I have used a smoke machine to diagnose that code many times. Vent valve on EVAP canister needs to be closed during that test.

 

[Mrt858]

They supposedly did on the third visit to the dealership

 

[Mrt858]

Haven’t been off road. This code started the second week after I bought at 400 miles

 

[Andrace]

The code is from a small link. I've attached the guidance from the service manual.


"(b) P045600: EVAP very small leak
In operation C, the leak detection pump creates negative pressure (vacuum) in the EVAP system and the EVAP system pressure is measured. If the stabilized system pressure is higher than second reference pressure, the ECM determines that the EVAP system has a small leak, illuminates the MIL and stores the DTC (2 trip detection logic)."

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