GLKwanter

2013 GLK 350, 140K. Got a P008A CEL 2 weeks ago. Read on here someone go through two fuel pumps before shop changed filter and that kept the CEL away. I've got a 600 mile trip through BFE Monday and dont need this stress. So far zero performance drop, just the code. I changed the filter last night, cleared codes, test drove, everything fine, no CEL. Filled tank this morning and soon as i restarted P008A is back. Let me clear it before, now its permenent.

While changing the fuel filter I pulled the negative battery cable and saw the battery is from 2019. Could an old battery cause the fuel pressure to read low or is it the fuel pump? If its the pump, how long before performance drop? I know no, some unanswerable questions.. *sigh*

andreigbs

If your battery is an AGM and it holds a good charge normally, I wouldn't suspect it here just because it's a 2019.

Searching other MB forums for that code, I found: "It turned out to be one of the flaps in the exhaust that open and close based on acceleration. A solenoid or valve failed and had to be replaced." There's an option.

Other places talk about a software update that may need to be done. Some places advise that you may want to look any conditions that might cause ignition misfire, an overly rich or lean fuel condition, or loss of compression.

You might've gotten a bad batch of gas or one (or more) of your fuel injectors is not spraying fuel optimally; maybe run a can of fuel system cleaner and make sure you always (always!) run premium fuel in your MB gasser.

GLKwanter

Shiiiiiiit man that's good researching. Sounds like it could be a parts rabbit hole. Think ill stop at the filter for now. I always fill up with 91 at Costco. Code just went away. I'm waiting for the drop in power, then i turn off/on to reset limp mode i read. I haven't paid anyone a dime to work on her yet. Wish i could nail it down myself.

Mmr1

Check battery voltage , do a load test. Most auto stores do it free. AGM can last 10 years, 7 is normal . But alternators go bad and Phantom loads can crop up . It’s probability not the battery. But with cold that is coming get it tested for free. Or buy a load tester for 50-60$. I had to replace my Regulator at 70,000 miles, charging was off.

GLKwanter

Yeah considering it's happened twice after driving 5 miles and filling up at Costco can't imagine it's the battery with no other symptoms, for 2 weeks. Starts right up, never hesitates.. yet sport mode is a blast.. freaking out a little about putting 600 mi on it with any issues, but everything I read about this seems very intermittent and nothing a restart doesn't clear. My biggest fear is being in the middle of nowhere with the whole family and the fuel pump completely dying, but I haven't heard any stories of this.
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I inspected the gas cap because I've read a few people surmise that was the issue, but no one who said it clearly was. I bought a new one off Amazon about a year ago, it looks fine to me.
Once it dropped the code after strong acceleration after filling up at Costco and once it did it after restarting after filling up at Costco. 🤷🏼

calder-cay

Sorry if this seems like an intrusion ... I would NEVER fill up our GLK350 (or heck, our 2001 Jeep!) with Costco or WallyWorld or grocery store gas.
Just because it show "91 octane" on the pump, doesnt mean there's nothing else rwong with it.

I've seen countless posts on Nextdoor about folks complaining how their vehicle is running like cr@p after they filled up at the discount, NO-BRAND station.
Turns out most ended up with water mixed with the supposed high octane fuel. Is that what we want for an MB?

We ONLY fill up with premium, at well-established name-brand company-owned stations.
(Many independently owned name-brand owners can skimp on who they purchase gas from)

GLKwanter

Oh yeah that's right, I heard about that undercover study the next door app put out. Glad I don't fear actual research, that would get in the way of fixing things.

Mmr1

I’ve used as do millions , Costco gas. I’ve had problems elsewhere. At my Costco hundreds an hour fill up . Costco doesn’t refine it.

Silver Shadow

Costco would not jeopardize a multi billion dollar company by buying and selling low grade adulterated gas. Costco gas is not the issue with the car.

John CC

Everyone gets their gas from the same fuel farms. The high volume stations are the safest bet.

GLKwanter

I have a BlueDriver Bluetooth Pro OBDII Scan Tool. No idea what half in the app means, but here's some stuff I found interesting from the attached saved reports.

While sitting idle in a heated garage with no CEL light on i kept scanning and clearing, scanning and clearing. See file Idle1.
I kept getting mbrace Codes B210D- Battery Voltage - Circuit Voltage Below Threshold
and B16 and 17 codes, "standing light 1 has a malfunction. There is a short circuit to positive or an open circuit."

But as soon as i pulled out cleared and scanned again they were gone and all i had was the P008A code left, even though light was still off. See file driving1.

Then sitting in the garage again after going around the block P008A CEL came on, again. Standing light codes come on in park, maybe that's normal.. not sure. Battery code didn't come back after driving.

Through a mode 6 and smog check in there too. I'm not sure how to read these. I see some oxygen sensor stuff in yellow not green. In July she was smoged and passed FWIW.

Part No on the 2019 battery is h7agm. It's an AMG. Has a triple A sticker on it that includes the part number.

John CC

In the ModeSix file all the yellow tests did not complete. That isn't a failure, more like "I didn't get to that yet". If you cleared everything then it'll show that until the tests are run to completion.

GLKwanter

https://www.benzworld.org/threads/20...-help.3084753/

I had the gas smell and swapped the cracked white cover a top the fuel pump, passenger side, few months ago. I remember seeing some discolored pins. Wonder if this is it..

Mmr1

You said you bought a fuel cap off Amazon . Made in some far eastern country for cheap? Order one from FCP euro, you might get lucky .

GLKwanter

Well, i could throw that money too, like i just threw at a new aftermarket fuel pump, cuz its only $100, returnable through amazon, and less than I'm going to get anyone to charge to diagnose this code as directly as i read a dealer could (who wanted $575 for a pump locally).. but wouldn't a human be able to tell if a gas cap wasn't sealing right? I've never read anyone come back and say 'That was it!'

Pump wont arrive till after the trip though. **fingers crossed**

Mmr1

Aftermarket Chinese has gotten insanely bad over the last years. I’ve heard of 7 bad alternators on a car. You really should YouTube about junk Chinese parts. I had 5 bad starters each failing in a week. My friend had a fuel pump fail in a few hours . Get it diagnosed and stop using aftermarket. Or go to FCP euro. They have lifetime warranty on everything they sell, yes oil, Brakes , wipers! Everything! Your problem could be what you purchased !

GLKwanter

3 years 36,000 miles is plenty warranty for any fuel filter.. I read about A-Premium on Reddit, many positive replies. The Chinese VVTs I put in 5k ago were same build quality I took out that was factory, and part of the common m276 startup rattle fix.

Mmr1

Maybe a bad Fuel Pressure Sensor ?

GLKwanter

I believe that came new top of the fuel filter I replaced.

Silver Shadow

It seems to be a separate part. FCP Fuel Pressure Sensor

GLKwanter

I've seen it can come separate too, kinda confusing because it was already mounted into the top of P/N: MB-221470189028 from autohaus, that I installed.

Mmr1

That is a low pressure code ? Wouldn’t measuring the pressure with a gauge be the next step?

GLKwanter

Well, i mean, sure if you want to think things through, but if you can return anything to zon why not parts chuck
..but hey since the zon pump will arrive after a fuel injection pump pressure tester gauge kit i just ordered for $31, also from zon, lets "test" first, maybe tomorrow
I am curious wtf is going on at idle, cuz that's when I've seen the CEL trip twice, and when you read about a P008A its often acceleration that it trips and performance lags. I'm half a mind to think its electrical cuz of this

To be continued...

GLKwanter

Well now, that can't be good. I'm not even sure what the fuel pressure is supposed to be in a GLK, but I mean, that's all over the place. New aftermarket pump will be here Friday. Let's hope it lasts long enough for another 1 minute video.

Mmr1

Another aftermarket cheesy chinesey? I hope it’s not.

FCP euro has lifetime warranty and German aftermarket. Good luck 🍀