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Discussion Starter #1
I just changed the spark plugs on my 09 GL 450 and I noticed the car jerk sometimes when I stop at a red light. Now the check engine light came on.
Anyone encountered such a problem before. Is it that I just need to clear codes?

Any experience?
 

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The simplest way to diagnose is to reverse what you did. Reinstall the old spark plugs as any new faulty spark plug can cause misfiring.
Did you also feel that the engine is under powered?
Did you experience overheating with the new spark plugs?

I completely agree with ronsbenz1956. He asked you (twice) to post the codes you got. Also provide us with the make and model of the code reader you used.

I hate using generic OBD II readers with these cars. But you know; something is better than nothing as long as the resulted error codes are not misleading.
Mercedes-Benz are meant to be diagnosed with the Star Diagnostic Tool.
 

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I wouldn't jump the gun and put the old spark plugs back in! The check engine light can be caused by a number of things, such as a dirty mass airflow meter. I would read codes and go from there.
 

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Discussion Starter #7
I will post the codes soon.

I'm repairing the front suspension struts, so the car is actually on the quick jack. I became a hardcore DIYer all of a sudden. Considering what mechanics charge out here in Los Angeles area, that's the only way I can afford this car. I'm waiting for the suspension separator (tool I purchased on Amazon $16) to be delivered as well as the struts. Working on this car is much more fun than I thought. Here's a list of all the stuff I did by myself so far:
The prices are the estimates I got from the mechanics

1. Changed transmission oil and filter - $350
2. Changed the transfer case oil - $100
3.Changed the front and rear differential oil - $200
4. Changed the engine oil and filter - $300
5. Changed the front and rear brakes and changed the brake fluid - $1860 saved
6.Changed the spark plugs - $495
7. Still working on both front struts - I haven't asked but I estimate $2200
 

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Ha! I got quotes for the transmission service from two shops, both about $500. I changed front differential fluid for $12.00 and transfer case fluid for $10, and spark plugs myself for $77. But the rear differential, the exhaust pipe was in the way so the plug couldn't be reached. My oil change was about $95 with a Mann oil filter and 9.5 quarts of Liqui Moly 5W40. Crazy to pay people to do things that you can do yourself! I learned that 15 years ago with my first Mercedes. An indy wanted to charge me $200 labor to change the spark plugs, I found it very easy with only 8 of them and simply remove two screws that hold the coil, then there's the plug. My check engine light was on before I changed the spark plugs but the engine ran perfectly. After changing the plugs, it came back on, I doubt it has anything to do with the plugs. I don't recall the numbers for the codes but they corresponded to rich mixture left and right banks, and errant data from the mass airflow meter. So, I believe that may need cleaning. There is a spray cleaner product made just for those, you don't want to clean them with any other product. That said, mine couldn't run any more perfectly. But soon I may tear into it and access that MAF and clean it. It's the part that the air cleaner housing mouth attaches to with its round mouth, once in there I think it is easy to remove, clean and put back. We will see !!! I don't have an SDS, all I have is a generic code reader I got as a Christmas gift! So I am guessing either MAF or possibly an O2 sensor?? I am glad my suspension seems to be in great shape. I once owned a 1996 W202 C220 that acted crazy, RPM all over the place, engine dying.... cleaned the MAF and it was Perfect after that. I still have the can of MAF cleaner that I used...
 

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Yes having someone work off the clock or doing it yourself is always great. My independent isn’t available so I am doing this oil change myself. Getting everything from the dealers wholesale site for $60 is amazing. Oil for a little over $4 a liter is way better than even mobil 1 at Walmart.


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I just changed the spark plugs on my 09 GL 450 and I noticed the car jerk sometimes when I stop at a red light. Now the check engine light came on.

Anyone encountered such a problem before. Is it that I just need to clear codes?



Any experience?
After you saved all the money you may want to invest $300 for a SDS this will be the best investment you ever made if you plan on driving MB,a for a while.

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$300 is all for an SDS? I thought they were like double that, or more. Where should I go to buy one? Maybe I can be of help to other MBZ drivers in my area once I've got one. Plus, I have four Benzies here at my house so it would certainly come in handy. Wouldn't work for a Maserati though, I imagine.
 

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$300 is all for an SDS? I thought they were like double that, or more. Where should I go to buy one? Maybe I can be of help to other MBZ drivers in my area once I've got one. Plus, I have four Benzies here at my house so it would certainly come in handy. Wouldn't work for a Maserati though, I imagine.
That's what I paid, I used a computer that I already had, software and a VAS passthru device where just under $300.
It's complete Xentry 2018 SDS with EPC and WIS.
Works only on vehicle 2002 and up.


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Discussion Starter #13
After you saved all the money you may want to invest $300 for a SDS this will be the best investment you ever made if you plan on driving MB,a for a while.

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\
First time I ever heard SDS. What is it?
 

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SDS is a computer/system that plugs into your car's OBD port and reads codes, but the SDS is more than just a code reader and is specialized just for Mercedes Benz automobiles. It will tell you more, and do more than just a generic code scanner. Pretty handy if you have a Mercedes that you plan to have for a while, and intent to do maintenance and repairs on it yourself. Myself having four Benzos, probably should have gotten myself an SDS a long time ago.
 

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Discussion Starter #15
SDS is a computer/system that plugs into your car's OBD port and reads codes, but the SDS is more than just a code reader and is specialized just for Mercedes Benz automobiles. It will tell you more, and do more than just a generic code scanner. Pretty handy if you have a Mercedes that you plan to have for a while, and intent to do maintenance and repairs on it yourself. Myself having four Benzos, probably should have gotten myself an SDS a long time ago.

There must be a different (or proper name) for this SDS. When I search it on Google, I get Safety Data Sheets.
Anyone know the actual or correct name?
 

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My engine shut off at a traffic light and again when parking and I had a check engine light illuminated... The first thing I would do after the spark plugs, is clean the MAF (mass airflow sensor) using the proper exact cleaning spray product. Because of the size of these vehicles, it is not easy to reach, you need something to stand on but it can be accessed, removed, cleaned and put back. Use a code reader and clear the codes before start-up. Maybe your check engine light will go off and it will run fine again. If not, a new Bosch replacement is about $72 on Amazon, they have some other brands that are cheaper, but for me I would get the Bosch unit. I cleaned mine, cleared the codes (It indicated rich fuel mixture both banks) and it has been fine since. It's only been a day though. After a week of no check engine light and no stalling, I will declare it a success. If it acts up again within a week I'll buy a new MAF.
 

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Discussion Starter #19
My engine shut off at a traffic light and again when parking and I had a check engine light illuminated... The first thing I would do after the spark plugs, is clean the MAF (mass airflow sensor) using the proper exact cleaning spray product. Because of the size of these vehicles, it is not easy to reach, you need something to stand on but it can be accessed, removed, cleaned and put back. Use a code reader and clear the codes before start-up. Maybe your check engine light will go off and it will run fine again. If not, a new Bosch replacement is about $72 on Amazon, they have some other brands that are cheaper, but for me I would get the Bosch unit. I cleaned mine, cleared the codes (It indicated rich fuel mixture both banks) and it has been fine since. It's only been a day though. After a week of no check engine light and no stalling, I will declare it a success. If it acts up again within a week I'll buy a new MAF.

Thank you Tonylinc. I will perform this service immediately after I finish replacing the struts.
 

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Discussion Starter #20
Hello TOnylinc,

How did you remove the Mass Airflow sensor ? Is there a clip holding it?
By yourself or did you take it to a mechanic?
 
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