Symptoms:
- Code P0455-Evaporative Emission Control System Leak Detected (no purge flow or large leak).
- During first few miles of driving, I hear a tick-tick-tick-thump sound coming from the rear of the car that is not related to tires/engine/speed/etc. The thump sound is pretty loud. The tick-tick-tick sounds like some type of piston-actuated pump. After >10 miles or so of driving, these sounds stop.
- After putting gas in tank, car will not start without pumping gas pedal.
- When removing gas cap, there is no ‘rush of air’ sound.
All of this started two weeks ago with no previous issues.
I know that the gas cap is one of the top items for this code but the seal on the cap looks very good. In addition, the local Volkswagen parts department stated that they’ve never ordered one before for replacement. I’ve heard of garages doing ‘smoke tests’ on the evap system-what the heck is that? How easy is it to find all of the little hardware that might be causing these issues?
Are you in the habit of “Topping Off” your gas tank when you fill it? Squeeze every last drop in that you could? This over-filling can cause serious damage to your evap system…Fixing it is a job for a specialist…
A smoke test is when they blow smoke into your gas tank and watch for where it leaks out…Sometimes cars get reluctant to start after filling because the vapor generated when filling the tank is dumped into the air intake, flooding the engine…This points to the carbon canister no longer working as it should…Perhaps because it was flooded with liquid gasoline??
As Caddyman wrote. He covered it well.
Oh yeah-I overfill it. Guess I need to stop doing that. I don’t particularly want a specialist fixing it though. I have no problems ripping stuff out and replacing it if I know what to rip out and replace. Any idea where to start?
You probably need a new “carbon canister”…Your enthusiasm for repairing this might fade after to price one of these things…Sometimes you can find a serviceable one in a salvage yard…If you find a salvage vehicle, get the control valves and sensors too. It’s called the Evap System and some of the components can be well hidden…
Where is the canister located? I can at least try to bypass it first and see if it makes a difference.