[bluesy_cube]

Hello fellow Bimmer lovers,


I've recently replaced HPFP for my 2011 e92 335i xDrive.
Good thing I've got it under the powertrain warranty as I got it used from a dealer.

Anyways, since the replacement, I am keep getting an alarm everytime I start up the car.
With a warning, it says "Close gas cap" on my dash and the CIC shows "Please tighten the gas cap".
With the alarm, I get the CEL as well.

I've hooked up MHD to read the code, and it says:
321C: Fuel tank ventilation system and purge air system, minor leak: Leakage greater than 1.0 mm.

I could not find ANY INFO at all about the code 321C.

Here are two of my guesses:
1. When the dealer was replacing the HPFP, they messed up somewhere and there is a fuel leakage.(Possibly the fuel line or the HPFP itself)
2. Simple gas cap rubber gasket issue.

I wish the second case would be it, as replacing the gas cap would solve the problem....
But before I try anything, I'd like to get everyone's opinion!!



p.s.
I've seen cases that it might be DMTL pump, but I doubt it as it would throw out a different code.

[PichaDis11]

Originally Posted by bluesy_cube

Hello fellow Bimmer lovers,


I've recently replaced HPFP for my 2011 e92 335i xDrive.
Good thing I've got it under the powertrain warranty as I got it used from a dealer.

Anyways, since the replacement, I am keep getting an alarm everytime I start up the car.
With a warning, it says "Close gas cap" on my dash and the CIC shows "Please tighten the gas cap".
With the alarm, I get the CEL as well.

I've hooked up MHD to read the code, and it says:
321C: Fuel tank ventilation system and purge air system, minor leak: Leakage greater than 1.0 mm.

I could not find ANY INFO at all about the code 321C.

Here are two of my guesses:
1. When the dealer was replacing the HPFP, they messed up somewhere and there is a fuel leakage.(Possibly the fuel line or the HPFP itself)
2. Simple gas cap rubber gasket issue.

I wish the second case would be it, as replacing the gas cap would solve the problem....
But before I try anything, I'd like to get everyone's opinion!!



p.s.
I've seen cases that it might be DMTL pump, but I doubt it as it would throw out a different code.

That's a wild thought about the leak at the HPFP would cause that code. You'd have many sensors or misfire codes going on if that were the case. Like the code stated you have a problem in the air vent system. Why not have the dealer diagnose it since they were the last to work in the car?

[bluesy_cube]

Originally Posted by PichaDis11

That's a wild thought about the leak at the HPFP would cause that code. You'd have many sensors or misfire codes going on if that were the case. Like the code stated you have a problem in the air vent system. Why not have the dealer diagnose it since they were the last to work in the car?

Thanks for your thought.
Your statement makes total sense and I think I could leave HPFP alone.
The dealer is located like 1.5hr drive away and I cannot reach them during weekdays due to works.

Hopefully, I'd find the cause very soon!

[PichaDis11]

Originally Posted by bluesy_cube

Thanks for your thought.
Your statement makes total sense and I think I could leave HPFP alone.
The dealer is located like 1.5hr drive away and I cannot reach them during weekdays due to works.

Hopefully, I'd find the cause very soon!

you could diagnose this with INPA suite. I kinda went through a little bit of this few months ago with my 328. Replaced gas cap, DMTL pump etc. Turned out to be my fuel pressure regulator and it's o-ring on top of the gas tank was leaking.

[Zigarock]

What was the outcome here?

[Xdrive35i2014]

I have got a 321C code as well... what is it? how did you get it resolved?

thanks

[bluesy_cube]

Hey folks,

Sorry that I totally forgot about this post.

Code 321C means that literally there's a leak of the fuel fumes somewhere in the EVAP system.
You have to check the lines all the way from the
Gas tank -> Charcoal Canister -> Fuel Tank Purge Valve -> Throttle body
or
Gas tank -> Charcoal Canister ->DMTL pump

In my case, the Fuel Tank Purge Valve had the pipe disconnected from the Charcoal Canister, which made a major leak in the fuel fumes all the way from the gas tank into the engine bay.

[Xdrive35i2014]

Originally Posted by bluesy_cube

Hey folks,

Sorry that I totally forgot about this post.

Code 321C means that literally there's a leak of the fuel fumes somewhere in the EVAP system.
You have to check the lines all the way from the
Gas tank -> Charcoal Canister -> Fuel Tank Purge Valve -> Throttle body
or
Gas tank -> Charcoal Canister ->DMTL pump

In my case, the Fuel Tank Purge Valve had the pipe disconnected from the Charcoal Canister, which made a major leak in the fuel fumes all the way from the gas tank into the engine bay.

hey, looks like you live in Vancouver BC as well. Which shop did you go to to get your problem fixed?

thanks,

[bluesy_cube]

Originally Posted by Xdrive35i2014

hey, looks like you live in Vancouver BC as well. Which shop did you go to to get your problem fixed?

thanks,

DIY all the way!

[Xdrive35i2014]

Originally Posted by bluesy_cube

DIY all the way!

thanks. I live in a tiny condo with a tiny parking space. I just don't have the space to do any work on my car.

I took my car to CG motorsport and they replaced the gas cap. The code came back a couple of days later. I was told to bring my car in for some more diagnostics. I will ask them to look at all of these:

Gas tank -> Charcoal Canister -> Fuel Tank Purge Valve -> Throttle body
or
Gas tank -> Charcoal Canister ->DMTL pump

thank you so much!

[bluesy_cube]

Originally Posted by Xdrive35i2014

thanks. I live in a tiny condo with a tiny parking space. I just don't have the space to do any work on my car.

I took my car to CG motorsport and they replaced the gas cap. The code came back a couple of days later. I was told to bring my car in for some more diagnostics. I will ask them to look at all of these:

Gas tank -> Charcoal Canister -> Fuel Tank Purge Valve -> Throttle body
or
Gas tank -> Charcoal Canister ->DMTL pump

thank you so much!

CG Motorsports was the one I went initially for Code 321C

Simple hose disconnection underneath the engine and I was rated a full hour service for this.
Later, I found that my case was < 5 min issue...


They are great mechanics though!