shawnmichael

Hello again everybody. So yesterday I get a call from my wife and she says "Ok, seriously, now it's time to trade this in" Turns out the CEL came on but everything seemed to be running fine. I told her to stop by the closest AAP and ask them to pull the code. They said it was an "Evap Emissions, etc, etc" which turns out to be primarily related to gas cap issues. So here's the problem. I was the last person to fill up her truck and it was Sunday (two days earlier) and I know that I shut off the truck. (If it was her who filled it up I would be certain that she had done something like left it running).

So I start researching and it looks to be a fairly common problem with some people even going into details about how you can use sandpaper to rub the gas neck rim smooth and clean off, etc. I did that but it didn't look bad anyway. Rubbed it down, cleaned it up and then started it 5+ times afterward. Still have the code.

Anybody have experience with gas cap problems, the "evap emissions" code, or anything similar? What did you do to fix it? How did you clear the light?

bop11

2013, how many miles. It doesn't have to be gas cap related and if it hasn't reset after that many start-drive cycles ( you need to drive a min of miles, not just start stop) it probably isn't gas cap related. Carbon canister, tube fittings other things cause this. Get it checked by the dealer for actual problem. What is an AAP?

shawnmichael

50-something thousand. From other problems that I have had, I have no doubt it's probably something more serious than the cap. But...videos online and even AAP recommendations (that's Advance Auto Parts) I was told that it's by far the most common. At less than 60k miles, I would also be inclined to think that it's something stupid. But again, with all the other problems I've had, it'll probably be something more serious. Anyway, the guys at AAP are idiots and rude and she's been to two now (I asked her to go back today) and they don't even want to help. They are hesitant and angry that she asks them to read the code and they don't even try to sell her parts. Just read the code tell her "evaporative systems small leak and evaporative systems gross leak" and then walk away without so much as an explanation and/or do you need to buy a gas cap, filter, purge valve, etc. Blows my mind. TWO different AAPs. And btw, they said they can't read the actual code, only have the written definition. I say BS on that one. I can see getting CODE ONLY and having to cross reference but not the other way around. Those guys are a bunch of unhelpful turds.

So here we are, 2-3 years old and again, a part failure. But without taking it to the dealer and paying hundreds or a thousand dollars for a $100 part and labor, does anybody know any easier way to diagnose the problem? I CAN smell fumes so I am going to try to "sniff" it out sometime soon. Is there a schematic somewhere and shows these lines and where they run? I can look for obvious cracks/leaks, but don't really know how to find the parts of the system other than making assumptions based on vacuum lines running to/from the intake.

shawnmichael

So yesterday I told my wife that she should take it by O'Reilly Auto Parts (because two separated Advanced Auto Parts in Ocean Springs and in Vancleave were worthless) to get the code read, printed, and also they told me that they would provide a description and picture of a possible replacement part (Canister or valve). Since I was having trouble identifying info on the canister, I figured that this would give me a starting point.

As soon as I got it out of my mouth she said "it cleared". WTF? You don't think I'd want to know that? Basically she said that she filled up at some point and we didn't drive all weekend. Yesterday morning was the first time that she noticed that it was no longer on. So it cleared after almost exactly a week. Not sure if "the problem" went away or if it is just not reporting anymore. But for now, we're clear.

That being said, both my son and myself on separate occasions and unbeknownst to eachother (on different days) commented to my wife about how strong of an odor of fumes we smelt at/around the truck. Can't be coincidence that we had an Evaporative Emissions System Leak CEL code and commented that we smelt fumes.

bop11

Drive cycles can be quite long: road or engine speeds and time. Quicker if you have an OBI tool to reset.



If you feel your Mercedes Benz does not have any operational faults which would stop any emission monitor from setting go ahead and follow the Mercedes Benz drive cycle below.
Please take extra caution while performing drive cycles on public roadways. Drive cycles can be difficult to follow under normal driving conditions.
Computers and Control Systems: Monitors, Trips, Drive Cycles and Readiness Codes
Mercedes-Benz Drive Cycle
Drive Cycle Test Procedure
Note: The drive cycle test needs to be done two (2) consecutive times. Prior to driving the vehicle read the drive cycle instructions carefully and completely to ensure successful test result.
NOTE: Depending on engine temperature you may perform the testing starting with EVAP system (see step 7) or start with steps 1 through 4 or continue to step 6 (Air injection Diagnostics). It's very important to note that these tests are all based on engine temperature.
Drive Cycle Test Procedure Explained
1. OXYGEN SENSOR HEATER MONITOR - 02 Sensor Heater Diagnostics (do not interrupt this portion of the test). With the engine warm (greater than 80°C), and the transmission in Park position, proceed as follows:

- Start engine and increase engine speed to between 2,000 to 2,500 RPM for 2 minutes.

- After the 2 minutes, run engine at idle speed, with no applied load for 6 minutes (Air conditioning OFF, no throttle movements, no vehicle movement, etc).

- After this time period has been obtained proceed to step 2 below.

NOTE: If using a Hand-Held Scan Tool verify Step 1 test completion. This will be indicated by a check mark in the display field or the word PASS or COMPLETE.
2. OXYGEN SENSOR MONITOR - Lambda (02) Sensor Signal (do not interrupt this portion of the test, to be conducted directly after step 1 above has been performed). With engine temp greater than 80°C, and with transmission lever in position D (DRIVE):

- Drive vehicle for 3 minutes at 43 mph.

- After the 3 minutes has been reached proceed to step 3 below.

NOTE: If using a Hand-Held Scan Tool verify Step 2 test completion. This will be indicated by a check mark in the display field or the word PASS or COMPLETE.
3. CAT MONITOR - Catalytic Converter Efficiency Diagnostics (do not interrupt this portion of the test and must be conducted directly after step 2 above has been performed). With engine temp greater than 80°C:

- Drive vehicle with transmission still in position D for 3 minutes at 47-55 mph.

NOTE: If using a Hand-Held Scan Tool verify Step 3 test completion. This will be indicated by a check mark in the display field or the word PASS or COMPLETE.
4. FUEL ADAPTATION MONITOR - Self-adjustment of the air/fuel mixture (do not interrupt this portion of the test and must be conducted directly after step 3 has been performed). With engine temp greater than 80°C, proceed as follows:

- Place transmission into Park position and allow engine to idle. insure no load. (i.e. Air conditioning OFF, power accessories OFF) for 3 minutes. NOTE: If using a Hand-Held Scan Tool verify Step 4 test completion. This will be indicated by a check mark in the display field or the word PASS or COMPLETE.
5. EGR SYSTEM MONITOR - EGR System (Emission Vacuum Diagnostics): No DTC codes should stored for the intake manifold pressure sensor and EGR pressure transducer during this portion of the test. With the engine temperature at 80°C:

- Start and Drive vehicle (in D position) and then accelerate smoothly up to 2000 rpm, and then decelerate smoothly back down to 1100

rpm.NOTE: If using a Hand Held Scan Tool to verify test completion. This will be indicated by a check mark in the display field or the word PASS or COMPLETE. After this test step has been completed, turn ignition OFF, wait 10 seconds and repeat this test step again.
6. AIR INJECTION MONITOR - Air Injection Diagnostics: (do not interrupt this test when performing this test step 6).

NOTE: It is recommended to perform this test while the engine is cool. You may choose to place a suitable auxiliary fan in front of the vehicle to force engine cooling. Continue test step: With engine temperature less than 40°C, the air conditioning OFF and the transmission in Park position;
- Start engine and accelerate engine speed to 1450 rpm.

- Allow engine to run at this increased rpm until coolant temperature reaches between 70°C to 106°C.

- Allow engine to run with increased rpms for 7 minutes.

- After the 7 minute time period has been reached, stop the vehicle, place gearshift lever into Park position and allow engine to idle (with no load) for 6 seconds.

- Turn the ignition OFF, wait ten seconds and repeat this test step.

- Note that when testing the air injection system, the engine coolant temperature must be at the same temperature as when before the ignition key was switched off in the prior test step.

NOTE: If using a Hand-Held Scan Tool to verify Step 6 test completion. This will be indicated by a check mark in the display field or the word PASS or COMPLETE.
7. EVAP MONITOR - Fuel System Leak test (EVAP): No DTC codes should be present in memory for the EVAP canister purge valve, fuel tank pressure sensor, or the shut-off valve.

Note: Prior to performing this test (7) step:

- Ensure the fuel tank fuel level is between 1/4 and 3/4 full and

- The engine temperature less than 100°C with air intake temperature less than 45°C.

- With the transmission in Park position, start and idle engine for 20 minutes, with no load.

- Note that if after the 20 minutes of idling and no readiness codes were set, consider driving the vehicle for an additional 20 minutes.

- After these 20 minutes has elapsed, turn ignition OFF, wait 10 seconds and repeat this test step again.

NOTE: If using a Hand Held Scan Tool to verify Step 7 test completion. This will be indicated by a check mark in the display field or the word PASS or COMPLETE.
Completing the above outlined drive cycle should set the proper readiness flags and complete the necessary emission monitors required to pass the emissions test.

Woof

Good morning. I found your thread and have a similar problem. Yesterday, after driving for 90 minutes, I came to a stop light and my car was chugging - the CEL was on and the idle was very rough. I had to put it in neutral to keep it from stalling. I made it home and did a google search which mentioned the gas cap (my tank was filled the day before). I opened the cap and closed it and now the CEL is off and the car seems to be idling fine, in the driveway. I am nervous to drive it now and have an appointment on Monday at the dealer.
I think this might have been the problem once before - I started it in my garage and the CEL was on, and the idle very rough. I took it to the dealer and they didn't mention why it did that - I think they said it was a system update. Probably bs now that I think of it.
Mine is also a 2013 and I have 48,000 kms (28,000 miles) on it.
So my question is - would the gas cap not being closed properly (although it seemed to be) cause the rough idle?
thank you for any light you can shed on this.

Mmr1

Woof

it seemed to be in place - I loosened it and closed it again. Maybe he hadn't tightened it 100% at the gas station. But would this cause the rough idle?

shawnmichael

Here's what I learned ... the purpose of the 'evaporative emissions system' is to capture gasoline fumes and prevent them from venting into the atmosphere (some hippie invention). Apparently in some world I've never lived in, this was such a problem that the entire world smelled like gasoline. Anyway, the fumes travel back up forward and get captured in a charcoal canister before (I believe) going into the intake somewhere via a vacuum line. So ... if that is how the system is connected and if there is a problem in the system, then yes it is technically possible that a vacuum leak could cause a rough idle. Note that there's a little uncertainty in 1) how exactly the system is designed and hooked up and 2) whether or not a vacuum leak would be bad enough in the EES system to cause a rough idle AND also be intermittent. I think it's unlikely. I'd be curious to see what code you were spitting out. My son's Jeep Wrangler had the same symptoms it was also intermittent; putting out cylinder misfire code. It ended up being a bad injector. I'm sure that'd be fun to replace on a Mercedes.

Woof

Very interesting. I am going to ask at the dealer for their explanation, assuming the rough idle and possible loose gas cap are linked. I don't know how to see the error code - there are no messages now.

shawnmichael

Most parts stores can/will read the code with a scanner.

Woof

Woof

Good morning Shawn Michael.

I wonder if your GLK still has this intermittent problem. Mine does. Yesterday was the 3rd time the CEL came on the day after a fill up, with rough idle. When I got home, I turned the car off and restarted it and the CEL was off. The dealer was unable to find the problem as it isn't happening when I take it in. They replaced a fuel injector (covered under the extended warranty thankfully) in March 2019.
I have a mobile mechanic coming to the house today to take a look, I trust him much more than the dealer, and thought I would check in with you to see if this has happened again with your car? I turned my car on this morning and no CEL.. what the heck is this... each time about 18 months apart. Mileage was 21773, 29750 and 36056. Otherwise this car has been problem free. thanks for any insight you can share.

shawnmichael

No further insights, sorry. Best thing I did was go buy a Lexus. I was sick of being told by MB that if I have spent more money, I'd have gotten a better car. They literally told me I bought a $45k junket.

I just last month spent $62k on an awesome GX460 (after owning a $54k GS350 for 5 years) and haven't had to worry anymore about the constant maintenance and repair problems that I had with the C300 and GLK.

Woof

OMG what a beauty!!! I think that's a great solution My Benz has been trouble free except for this, although I've been tempted to get a new toy I mean car... So the mechanic spent time looking at codes and doing some tests, he strongly believes it's gunk built up in the fuel injectors that causes this intermittent problem. He suggested putting an additive once a month, so I'll do that and see how she goes. thanks so much, take care and enjoy your new Lexus !!

shawnmichael

[size=16px]I seriously doubt that a cleaner will do anything. The evaporative emissions system sucks fumes out of the system to protect mother earth, nothing more. The code I had is telling me/you that the system is unable to pull a vacuum, insinuating a leak somewhere in the system. That's why the first excuse they always give is to check the gas cap. You shouldn't have any symptoms at all of the truck running bad, it's just a nuisance.[/size]

[size=16px]All that being said, in less than 3 years, I replaced wheel bearings, brake rotors, rear shock mount, auxiliary battery (start stop) failed, seat stitching was coming undone. I was fed up, and when the dealer told me I needed to pay more to get better quality, I told him his logic was flawed and promptly sold the GLK private party.[/size]

[size=16px]Good luck with it, but honestly I think it's nothing more than a nuisance.[/size]

Woof

I'd change vehicles too if I had all those issues and I've decided that if this particular problem continues, I'll get something else. I can't stand an unreliable car. And it's always fun to get something new

Springbrd9

Same issue. Had to replace a gas cap on a 2013 ML 350. It took about a week, as the dealer said, and the light went off. Dealer is awesome, they told me to check the gas cap before going to them. Sure enough, I could pull it off without unscrewing.

jslife17

Not sure if its related, but I had issues where I was filling up at 94 octane and it would cause issues with my GLK(not start, CEL came on, rough idle). I switched to 91 and I had no issues ever since. Been over a year now.

John CC

That makes no sense...

jslife17

Swear to god. No error codes, starts no problem. no CEL. No rough idle nada.

MBKLUE

You may have filled up with a tank of "bad" 94 octane but it had nothing to do with the octane.

John CC

Yeah, the only difference when you fill with higher octane than necessary is an increase in your cost per gallon, and maybe a slight decrease in MPG.