» » »

Pontiac Q&A

Ask Your Question

2009 Pontiac G8 Question: Is it normal for the P0455 code to always come up when engine is on?

 

Question

Sd2009, Woodbury, NJ, December 19, 2013, 17:06
 Rookie

In the past 2 years this code always shows up when I take the car to the dealer. About a year ago they found what they called a major problem, so far they have replaced the solenoid valve, rear evap canister, and left axle seal and also the fuel cap. Now a year later and the code is popping up again and they are telling me thesmoke test is negative. I feel like I purchased a lemon and need advice. Thanks

3 Answers
Flag This
  • Answer #1

    G. T. Service Center (4228 Answers) , Stephenville, TX - (254) 638-3236
    ProfessorG December 19, 2013, 17:48
    Profile_thumbnail
     Master

    Apparently they are not very useful; Have them run an EVAP test with the Tech2 and watch the Fuel Tank Pressure Sensor operation. There's not a leak per say, just the computer recognizes a leak if the pressure sensor is not reading properly.

    Reply
    Flag This
  • Answer #2

    cardocIII from Gillespie's Auto Service, December 19, 2013, 18:32
    Profile_thumbnail
     Master

    P0455 is a large leak, or also known as a weak vacuum test failure. One of the first tests the system runs is to open the purge valve so that the engine can draw a vacuum on the system, and it closes the vent valve so that the canister and tank pull into a vacuum. The vacuum level has to exceed 8" in water to pass this first test. Prof is correct about using Tech II to command the system to run this step with the bi-directional controls and monitor the fuel tank pressure sensor output. I've had the purge valves stick on these and not draw any vapors and so it can't go into a vacuum and the test fails.

    Reply
    Flag This
  • Answer #3

    Greg's Orange Auto (14194 Answers) , Orange, CA - (714) 361-9386
    globalhelper December 20, 2013, 06:24
     Master

    agree with both

    Reply
    Flag This