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Can't find EVAP problem not matter what I try...HELP!!!
Hello everyone,
I've been a long-time lurker on the forum and really appreciate all the guides you’ve shared—they’ve helped me a lot. I’m now in need of some extra help, so I’ve finally made an account.
Model:
2019 MINI Countryman Base (F60)
Problem:
I’m experiencing poor MPG (~19 mpg) and have two persistent codes: P0447 and P11C4. I can’t pass an emissions test because of this.
What I’ve Tried So Far (in no particular order):
Replaced gas cap twice.
Replaced purge valve three times.
Performed smoke tests three times – no leaks found, only smoke exiting from the vent filter near the rear driver’s side wheel well.
Performed vacuum test – holds vacuum with no issues.
Inspected vapor canister – air flows freely as expected in all directions.
Cleaned and tested the fuel tank pressure sensor with an oscilloscope – readings seem normal.
Checked the purge valve signal with an oscilloscope.
Inspected wiring – everything appears fine as far as I can see (though it's pretty cramped in there).
Some Backstory:
A few months ago, after fueling up with the engine running (yes, I know—lesson learned—it was 125°F outside, and I wanted to keep the AC on), my Countryman left me stranded. The engine ran very rough and then died.
I scanned for codes and found:
P0446 – Evaporative Emission Control System Vent Control Circuit
P0456 – Evaporative Emissions System Leak Detected (small leak)
P0172 – System Too Rich (Bank 1)
P11C4 – DMTL System Fault
After researching the forum, I found that the common culprits are often the gas cap or purge valve, so I replaced both. The car started running again—still a bit rough—but otherwise okay. However, over the past few months, my MPG has steadily declined.
The initial codes never came back, but P0446 (Evaporative Emission Control System Vent Control Circuit) and P11C4 persist, with P0450 (Fuel Tank Pressure Sensor Circuit) briefly showing up at one point.
I’ve tried everything I can think of, and I’m stuck. Any help or suggestions would be greatly appreciated!
All i can think of is a bad connection purge valve up front on the pins or wire. Damaged Wires, twisted wires. Maybe test with the car running and move the wires. Or one of the lines is not sealing all the way or air leak. Move it around as when things heat up or cool they can leak.
Gas Cap i would wipe out were the gasket on the gas cap seals just to make sure their is a good seal. On the flange and make sure the flange does not have metal bur or something on it preventing a seal even with a new cap.
I have tried with the car running and cold as well as after along drive, I think it's time to inspect every seal one by one, I will say that when I am filling up and the pump stops and I pull the spout out there is fuel slowly draining into the tank, only for a second but its there. Kinda similar how some have gas overfilling with a bad canister but with mine it doesn't constantly click before its full.
All i can think of is a bad connection purge valve up front on the pins or wire. Damaged Wires, twisted wires. Maybe test with the car running and move the wires. Or one of the lines is not sealing all the way or air leak. Move it around as when things heat up or cool they can leak.
Gas Cap i would wipe out were the gasket on the gas cap seals just to make sure their is a good seal. On the flange and make sure the flange does not have metal bur or something on it preventing a seal even with a new cap.
You gone through it pretty well.
Is there a place I can get the 3D models shown in these images? I always see the images online as clickable image maps but never the actual 3D file, I'd like to be able to rotate views and inspect further...
Have you replaced your leak diagnostic module? It’s on a vent line coming off the charcoal canister. There is also a dust filter on that too (where the smoke was coming out of during your smoke test) that can be replaced. Not a common issue on the F60’s but since you have done all the obvious that may be your culprit.
Is there a place I can get the 3D models shown in these images? I always see the images online as clickable image maps but never the actual 3D file, I'd like to be able to rotate views and inspect further...
Nope we dont have those and the MINI ETK does not.
I have tried with the car running and cold as well as after along drive, I think it's time to inspect every seal one by one, I will say that when I am filling up and the pump stops and I pull the spout out there is fuel slowly draining into the tank, only for a second but its there. Kinda similar how some have gas overfilling with a bad canister but with mine it doesn't constantly click before its full.
That is interesting, almost like there is some obstruction in the filler tube. Yeah, I had seen some messages up here and so I always stop the fill when the nozzle clicks off. No forcing 'top-off' fuel into it.
Strange little system.
I have a Jeep Gladiator that sometimes will shoot fuel back out the filler tube if the pump is not super sensitive and cuts off early. I usually have to listen to it while fueling and if starts to fill back up the filler tube I cut it off so it doesn't spit fuel out all over you hand and shoes. Then other times it fuels normal.
Will it spit fuel back out the filler tube ?
Is it slow every time to take fuel like there is an obstruction? That would kind of indicate a purge valve but you have replaced and checked those.
Strange it pops that fuel cap warning message. So it's like something is not 'sealed', because you have replaced the fuel filler cap, checked the purge valve, & you have done the smoke test.
That is strange. wonder why it is affecting your fuel mileage?
I got P0446 a couple of weeks ago (2018 F60). Cleared the code and it came back the next day. Cleaned the gas cap area, got the code again 1-2 days later. Replaced gas cap, 1-2 days and got P0446 again. Waited for evap valve to arrive. Installed today, is Bosch unit with same part number as original (by date seems like evap valve was original). Drove for a bit and damned code came back….arghhhh!
What is suggested as next step? Mini dealer is 15 hour (yes!) drive one way, so I typically do all the work myself…I wouldn’t trust any local mechanics in my small town.
Gas mileage seems normal, no rough idle or anything unusual otherwise.
Last edited by North of 60; May 13, 2025 at 06:48 AM.
I would look at my list above and unhook and rehook those lines. You are pulling air or have something leaking. Also check the pin connection at the Bosch unit and charcoal filter system.
Everything went together with a ‘click’ on the evap valve, but will disconnect and try again. I did not inspect the original valve but will do that just for knowledge, but it was dry on the exterior, no signs of a leak. I will trace the hoses back a bit in the engine compartment, inspect and ensure connections are good. After that I guess I will go to the rear and check the leak detection valve, filter and the charcoal canister connections for any visible damage?
Prices are higher for those items, not willing to just purchase and try out.
UPDATE:
I still have the problems mentioned above and was inspecting the wiring all the way back to the ECU yesterday, when ISTA guided me on how to inspect the inner membrane of the purge valve and sure enough it is torn. Here are some images incase anyone is interested, will update if a new OEM purge valve fixes anything.
How a purge valve membrane should look Membrane laying sideways completely loose in purge valve housing
