BimmerFest BMW Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
54 Posts
Discussion Starter · #1 ·
I have had this code pop up now 3-4 times after clearing it. I looked a little on here and other forums, but cannot find any straight answers. It looks like this could be a trans fluid leak (which would make sense since my car has been leaving little puddles behind when it sits turned on), and some say fuel pump issues. I have not the slightest clue what may be causing this. So if someone could point me in the right direction that would be helpful

Thanks ahead of time
 

·
Lost but making good time
'11 335xi; '03 330Ci
Joined
·
5,666 Posts
The transmission leak is unrelated.

DMTL is an initialism for "Diagnostic Module, Tank Leakage"--the tank in question being the fuel tank. This subsystem monitors your fuel tank for vapor leaks to the atmosphere. The people telling you "fuel pump" may have been thinking of the DMTL pump, a component of the leak-detection system. The pump periodically pressurizes the fuel tank while the DMTL monitors the leak-down time to detect ... leaks. :) On E46 cars the pump is a minor weak point. My old 325xi had its original pump fail, reported a few intermittent faults from the second, then soldiered on for years without ever failing or storing another fault code. IIRC, however, there is a specific fault code for the pump that is different from what you reported.

Things to check:
  1. Make sure you always fully tighten your fuel filler cap (until it clicks). Make sure the cap and seat are scrupulously clean. Ensure the cap is in good repair without visible wear or damage to the seal or springs. If you have any doubts, a new cap is less than $25 from a dealer. The cap is the most common cause, by far, of an actual vapor leak.
  2. If you are in the habit of "topping off" the tank when you refuel, break the habit. Stop fueling when the pump clicks off. Overfilling can cause problems with the evaporative emissions control systems. In particular, IIRC, if the vapor-recovery charcoal canister becomes contaminated with raw fuel, you may start seeing spurious fault codes until the excess fuel is vaporized and purged. (If it's heavily contaminated, i.e., flooded, it may never recover and would need to be replaced.)
These are emissions-monitoring faults only; they do not affect performance or safe operation of the car. Try those cheap/no-cost fixes first. The filler cap you can check/correct in minutes. Minor fuel contamination of the canister should clear itself in a month or so, depending on how much you drive.
 

·
Registered
Joined
·
54 Posts
Discussion Starter · #3 ·
Zeichen331 Thank you for the insight. I always add extra gas at the pump so I'll stop doing that and I'll inspect the cap as well for wear or tear.
 

·
Registered
Joined
·
5,349 Posts
Zeichen331 Thank you for the insight. I always add extra gas at the pump so I'll stop doing that and I'll inspect the cap as well for wear or tear.
Check the pump pressure at the Schrader valve. It's located on the engine fuel rail that is under the top plastic engine cover. Pressure should be at least 45psi.
 

·
Registered
Joined
·
54 Posts
Discussion Starter · #5 ·
Check the pump pressure at the Schrader valve. It's located on the engine fuel rail that is under the top plastic engine cover. Pressure should be at least 45psi.
How should I test the pressure? Do you have any pictures of this that I could see?
 

·
Keeping it surreal
Joined
·
43,253 Posts
How should I test the pressure? Do you have any pictures of this that I could see?
It`s a Shraeder valve, just like the one on your tires. After removing the plastic engine cover, you`ll see it right there. Autozone will probably loan (or rent) you a pressure gauge.

P.S.: That K&N CAI is not doing your engine any good (they`re known MAF killers on BMWs). The stock intake is a true CAI which out-performs the K&N....
 

·
Registered
Joined
·
54 Posts
Discussion Starter · #7 ·
It`s a Shraeder valve, just like the one on your tires. After removing the plastic engine cover, you`ll see it right there. Autozone will probably loan (or rent) you a pressure gauge.

P.S.: That K&N CAI is not doing your engine any good (they`re known MAF killers on BMWs). The stock intake is a true CAI which out-performs the K&N....
Right on, I'll check it tonight. Should the car be running when I check the pressure?
 
1 - 7 of 7 Posts
Top