Help with p0455 2019 tahoe 5.3

Jeremy Stephens · February 11, 2023

I am aware im posting for a 2019 in a 2018 subforum. The tahoe runs a year behind the trucks. I have a 2019 tahoe 5.3 that just gave a p0455 code. Mass evap leak. I do have a upr catch can installed but I don't think it is the culprit.

The only symptoms the truck has is a slight mileage drop and a smell in the cabin of used oil that comes and goes.

I do not have issues filling the tank with fuel, no gurgling or anything.

I did order a vapor can purge solenoid that installs near the throttle body just to have a starting point.

I have not seen any loose hoses.

Is there a repeat offender that causes this code?

Where else should I look?

newdude · February 11, 2023

1 hour ago, Jeremy Stephens said:

I am aware im posting for a 2019 in a 2018 subforum. The tahoe runs a year behind the trucks. I have a 2019 tahoe 5.3 that just gave a p0455 code. Mass evap leak. I do have a upr catch can installed but I don't think it is the culprit.

The only symptoms the truck has is a slight mileage drop and a smell in the cabin of used oil that comes and goes.

I do not have issues filling the tank with fuel, no gurgling or anything.

I did order a vapor can purge solenoid that installs near the throttle body just to have a starting point.

I have not seen any loose hoses.

Is there a repeat offender that causes this code?

Where else should I look?

Large leak would be a damaged EVAP canister, stuck open EVAP vent valve, stuck closed purge valve or blocked purge line.

Ideal thing instead of throwing parts at it is a scan tool and a smoke test. Smoking the system and then commanding the vent solenoid and purge solenoid would verify their operation. It can also pinpoint a leak elsewhere say the fuel sending unit, the top rusted and a hole opened up.

Edited February 11, 2023 by newdude