OK, so after on/off, on/off and finally on, I had enough. I took the car to my tech and replaced the evaporative fuel valve and fuel tank vent valve for which the fault codes were indicating . It's only been a week but all seems well.

However I did note something right away as I pulled away from the repair shop. It may be my imagination but after the these repairs the growl of the exhaust sounds louder. Could this be? Prior to, when just leaving a stop light at a normal speed the growl would be subdued and only get louder if I rapidly accelerated. Now the growl is there as I begin to accelerate at slow speeds.

I would like to know if anyone has experienced this or is aware of this from a technical point of view.

 

If the vacuum hose came off the bypass valve it could cause the exhaust note to change like you described. Same as pulling fuse #22. Or it's just the placebo effect of something changed after it was fixed. Or the extra 10hp after the oil change.

 

What does pulling fuse #22 do?

 

Disables the exhaust bypass valve operation, via kills power to vacuum pump. And valves default mode to open. Which is the same as if you had a vacuum line off "leak" but then you would hear the compressor running @100%.

 

I saw this thread and thought it was similar to my issue, wanted to see what the forum says.
i changed my oil, followed the instructions of removing the throttle body, everything went well. However not right away, second time running the car i had an "Emission Service Required Error". i noticed that one of small tubes for throttle body came loose/off, i suspect it is a sensor. I reattached it but still have the error. Car has been turned off multiple times, even used the Foxwell 520 to find an error code w/out success. Any thoughts or experience w/ this situation, thanks.

 

Vantage or db9? Had the same with db9. I run the car hard for a couple of miles when she was nice and warm and code went away.

 

Vantage V12S. I will try, i did take it around neighborhood but no better. It runs fine. so hopefully it is one of those British electronic glitches

 

his explanation makes sense and is counter to what many suggest in this thread.

 

how very dare you…I think it’s the Italians that have the electrical reputation…😂

 

I actually own Denver_V8V's Vantage now and I'm still chasing that emission light! I've changed the gas cap and the purge valve due to a P0442 code (small EVAP leak) and that hasn't seemed to solve the issue. I've got a smoke machine coming and hopefully that'll help me figure out what's causing it to throw the code. What is good to find out is that the fuel vent valve has been replaced recently, so that's unlikely the issue.

 

This old thread just saved me a few $100s. I got the Emissions systems service light come up randomly one day and would keep showing up at every start. Was thinking about getting an appointment at my local dealer to get it checked and cleared which I'm sure they'd've charged a pretty penny for.

Ended up opening my gas cap like some folks suggested and I drove it ~10 short city trips and it just stopped giving the alert. Now I just hope that was permanent and that it won't come back anytime soon.

 

Any update? I'm the latest victim..this morning while driving to yoga class. 09 V8V

 

Yes it went away after driving a little while. However I've noticed it will intermittently come back maybe once or twice a month. I just do the same fix and it goes away again. Good luck!

 

The same FIX? That's not doing anything except boosting your ego.

 

Actually I believe the O2 sensors are NTK. Stuart at AP Velocity has the part number.