DB11 V12 Evaporative Emissions System
Discussion
Over the last several days, I've completely rebuilt the evaporative emissions system in my 2018 DB11 V12. My mission was to replace all components in the system without any visit to an AM dealer.
I did this because I was occasionally (about every 100 miles which is a typical EMS system check) receiving a CEL (a P0456), defined as a very small vapor leak. Without the proper test equipment I could not test the system to pinpoint the exact failure point so I renewed every component in the system. The ONLY component not renewed is the capless fuel fill port (what an absolutely stupid design). I had to hope some other component failed in the system as the capless unit would have to be AM parts at an exorbitant price. One other part(s) of the system that could fail is any cracked or leaking lines. These too, I did not check, but was hopeful not the problem. I would have had to use a smoke machine to test for failed lines.
First, I tackled the back end of the system which starts with the carbon canister along with a vapor leak detection pump. These are in an assembly found in the left hand rear wheel well (on a LHD NA car). It looks like this:
For the vapor leak detection pump, I found it to be a fairly common Bosch part easily obtainable from parts stores. This same pump is used on a number of other cars. For the carbon canister, I searched and searched but could not find the source of this part, so I elected to open the canister and rebuild it completely with new carbon material I easily found in the commercial marketplace. The canister has a "clean" and a "dirty" side separated by a spring loaded, double sided filter. The canister is divided about 1/3, 2/3rds - 2/3rd the dirty side, 1/3 the clean side. This rebuild went easily, I resealed the canister, the assembled the new pump and filter, then back in the car.
The "other" end of the evaporative emissions system is found under the bonnet. On the V12, AM used a pair of purge valves which are typical failure points in this system. The purge valves are located here:
Some disassembly has to be had to reach these two components. I won't go through those gory details, but should be intuitive from the picture. Here too, I found the purge valves to be a somewhat common Bosch component, used on a number of other cars from different manufacturers and easily acquired. I actually purchased these two purge valves on Amazon.
One last component (a pair, aft of the purge valves) is an anti-siphon (one way) valve found in the lines that leave the purge valves, and before those lines attach to the TBs. These were easily tested as any one way valve would be.
Now after this rebuild, I've put about 300 miles on the car with no more CELs, no more P0456s. Very satisfied with the results and the entire rebuild cost about $150 USD.
I did this because I was occasionally (about every 100 miles which is a typical EMS system check) receiving a CEL (a P0456), defined as a very small vapor leak. Without the proper test equipment I could not test the system to pinpoint the exact failure point so I renewed every component in the system. The ONLY component not renewed is the capless fuel fill port (what an absolutely stupid design). I had to hope some other component failed in the system as the capless unit would have to be AM parts at an exorbitant price. One other part(s) of the system that could fail is any cracked or leaking lines. These too, I did not check, but was hopeful not the problem. I would have had to use a smoke machine to test for failed lines.
First, I tackled the back end of the system which starts with the carbon canister along with a vapor leak detection pump. These are in an assembly found in the left hand rear wheel well (on a LHD NA car). It looks like this:
For the vapor leak detection pump, I found it to be a fairly common Bosch part easily obtainable from parts stores. This same pump is used on a number of other cars. For the carbon canister, I searched and searched but could not find the source of this part, so I elected to open the canister and rebuild it completely with new carbon material I easily found in the commercial marketplace. The canister has a "clean" and a "dirty" side separated by a spring loaded, double sided filter. The canister is divided about 1/3, 2/3rds - 2/3rd the dirty side, 1/3 the clean side. This rebuild went easily, I resealed the canister, the assembled the new pump and filter, then back in the car.
The "other" end of the evaporative emissions system is found under the bonnet. On the V12, AM used a pair of purge valves which are typical failure points in this system. The purge valves are located here:
Some disassembly has to be had to reach these two components. I won't go through those gory details, but should be intuitive from the picture. Here too, I found the purge valves to be a somewhat common Bosch component, used on a number of other cars from different manufacturers and easily acquired. I actually purchased these two purge valves on Amazon.
One last component (a pair, aft of the purge valves) is an anti-siphon (one way) valve found in the lines that leave the purge valves, and before those lines attach to the TBs. These were easily tested as any one way valve would be.
Now after this rebuild, I've put about 300 miles on the car with no more CELs, no more P0456s. Very satisfied with the results and the entire rebuild cost about $150 USD.
McButterpants said:
Did you have a way of reading the P code? Every code reader i try fails to read anything at all. I know that you need the AMS system to get into all the details but I just want to check for basic codes.
I've no problem reading any "power train" codes on this platform. P-codes produce the infamous CEL (check engine light). These codes are not proprietary to any auto manufacturer. Auto builders complying with US/Euro EPA emissions standards must use the SAE standard protocols and provide capability for these codes to be accessed openly. I have several scan tools, some cheap and simple and some much more complex and they all work to read P-codes on my DB11. An older scan tool wouldn't work. The scan tool must be CAN-BUS compatible but you would have to be using a tool probably back before 2006 for that to be the case. Other monitored systems on the car (and all other cars) do get proprietary. These include
B-codes - body and security faults
C-codes - chassis faults
U-codes - networking faults
Any of these faults I cannot read without an AM system, which no aftermarket suppliers support on the DB11 platform, to my knowledge.
thanks, yea not sure. I had one that was an innova that was maybe $60 and at the time i had both low voltage and misfires and it read absolutely nothing.
Now i lost that one and tried another innova $30 cheap one and again, nothing.
I am going to try a Foxwell nt530 next. Aston said it sounds like an evap issue but i made an appointment that i'll keep if the foxwell cant read it.
Now i lost that one and tried another innova $30 cheap one and again, nothing.
I am going to try a Foxwell nt530 next. Aston said it sounds like an evap issue but i made an appointment that i'll keep if the foxwell cant read it.
QUESTION: Are you getting a check engine light for misfires, etc? If you are not, then no codes are being produced to be read by a scan tool.
If the CEL is illuminated, then any recent CAN BUS scan tool should read it.
When dealing with the emissions fault described above on my DB11, I used one of my tools, an Autel MX808 and it read the following (and I deleted same codes with the delete feature which even my cheap tools have):
If the CEL is illuminated, then any recent CAN BUS scan tool should read it.
When dealing with the emissions fault described above on my DB11, I used one of my tools, an Autel MX808 and it read the following (and I deleted same codes with the delete feature which even my cheap tools have):
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