PO455 TROUBLE CODE

MCAUTODOC

MEMBER
2004 CHEVROLET IMPALA

Computer problem 6 cyl Front Wheel Drive Automatic 164169 miles

VIN #2G1WF52E549116832

Getting trouble code PO455/evap. Emission control system leak large; also got PO455 pending as well. Have replaced the gas tank cap (was loose & worn out) but code continues to come up. I don't have a scanner, just an Actron code reader. The below info is what I was able to get off freeze frame; would like if someone could narrow it down for me, thanks.
THROTTLE POSITION) 0.0
ENGINE RPM) -
LOAD VALUE) 2.7
MAP SENSOR) 42
AIR FLOW RATE) 4.10
COOLANT TEMP) 185
SHORT TERM FUEL TRIM 1) -5.1
LTFT2) -6.3
STFT3) -42.4
LTFT3) 68.7
VEHICLE SPEED) 0
FUEL SYSTEM 1) OPEN
FUEL SYSTEM 2) NA

2 Replies

KEN L

MASTER CERTIFIED MECHANIC
42,895 POSTS

Hello,

What this code is telling you is that there is a leak in the evap system or a lack of vacuum to it. Now you have already replaced the gas cap so we will figure on that being good. Now I have included a pic of the vacuum hose routing to the evap canister. I need you to check the vacuum hoses and the canister for any visible damage or broken or disconnected vacuum hoses. Let me know what you find and we will go from there.

You could also have a purge solenoid problem with a vacuum leak headed to the valve. Here is a guide that shows the repair on another car but its the same idea on all cars.

https://www.2carpros.com/articles/evap-system-code-repair

Please let us know what happens.

Cheers, Ken