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GL350 BlueTec
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210 Posts
What auxiliary battery part number does my 2012 GL350 require and who sells this battery and who can install it?
Hello. Your local MB dealer will do all of the above and you won't have to worry about part numbers. If you're looking to do it yourself then the part number is on the battery itself. Any local mechanic will do it. GL.

 

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2003 S500 2007 GL450
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4,089 Posts
The aux battery is a small 12vdc 1.2Ah SLA (Sealed Led Acid) battery. These small batteries are used in hundreds of different application, from burglar alarms to ride-on toys. You can buy one with the Mercedes star on the label for about $50-75 - or you can buy the same battery for less than $20 by buying a generic/store brand/independent brand (e.g., Duralast or similar)..

Installing the battery is an interesting job, requiring some strength. Both batteries are underneath the passengers seat (LHD vehicles), and you have to remove the large starting battery to access the aux battery.

This video shows the job on an earlier ML, but the job is the same. Watch this and see if you are interested in a DIY job.
 

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2012 Mercedes-Benz GL350
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5 Posts
Discussion Starter · #4 ·
Thanks to all! The information was helpful and I drove to my local Mercedes dealer and bought the battery. I installed the battery with a little bit of effort but well worth the savings of a $267.00 installation fee.
 

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Dallas, Texas
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13,374 Posts
Thanks to all! The information was helpful and I drove to my local Mercedes dealer and bought the battery. I installed the battery with a little bit of effort but well worth the savings of a $267.00 installation fee.
White battery warning has diapered?
 

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2012 Mercedes-Benz GL350
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5 Posts
Discussion Starter · #7 ·
So 24 hours later I get a ”Check Engine” light and take the vehicle to Auto Zone for a check engine scan. Auto Zone scans for codes and there are none. I drove over to O’Reily‘s and same thing no code or codes! Can this be an auxiliary battery issue?
I hate to take it to the Mercedes dealer! How do you clear the check engine light?
 

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GL350 BlueTec
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210 Posts
So 24 hours later I get a ”Check Engine” light and take the vehicle to Auto Zone for a check engine scan. Auto Zone scans for codes and there are none. I drove over to O’Reily‘s and same thing no code or codes! Can this be an auxiliary battery issue?
I hate to take it to the Mercedes dealer! How do you clear the check engine light?
Hello. The aux battery will not trigger a check engine light. Your check engine light is a separate issue. The check engine light was triggered by the system when it was running basic diagnostic upon starting the car or if you hit something or faulty part. If no codes present that means that the system triggered the check engine light and stored it immediately in the memory as an old code, since the part that failed or is failing became operational within given parameters again.

You can reset it with an MB obd reader. The check engine light will turn off, if it's not triggered again within 15/30 starts of the car. GL.
 

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2012 Mercedes-Benz GL350
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5 Posts
Discussion Starter · #10 ·
Hello. The aux battery will not trigger a check engine light. Your check engine light is a separate issue. The check engine light was triggered by the system when it was running basic diagnostic upon starting the car or if you hit something or faulty part. If no codes present that means that the system triggered the check engine light and stored it immediately in the memory as an old code, since the part that failed or is failing became operational within given parameters again. You can reset it with an MB obd reader. The check engine light will turn off, if it's not triggered again within 15/30 starts of the car. GL.
3-4 months ago I had the AEM Approved Emissions Modifications completed and last Friday the “Check Engine” came on. Auto Zone and O’Rileys scanned my 2012 GL350 and they were unable to locate any codes. Today I drove over to a local mechanic who rescanned my vehicle. His scan too located “P203D reductant level sensor circuit high” which I believe Is an emissions issue covered by the AEM warranty. I called the local Mercedes’ dealer and awaiting a call back for additional days down. Any additional ideas
 

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GL350 BlueTec
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210 Posts
3-4 months ago I had the AEM Approved Emissions Modifications completed and last Friday the “Check Engine” came on. Auto Zone and O’Rileys scanned my 2012 GL350 and they were unable to locate any codes. Today I drove over to a local mechanic who rescanned my vehicle. His scan too located “P203D reductant level sensor circuit high” which I believe Is an emissions issue covered by the AEM warranty. I called the local Mercedes’ dealer and awaiting a call back for additional days down. Any additional ideas
Hello. The dealer will tell you to bring it in and they'll check it out. Since you completed the AEM modification then it's all covered under warranty. Your code is related to a NOx sensor. One or both of them. Pretty common on the diesel bluetec. GL.
 

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2010 ML350, 1977 300D, 1961 O321H
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14 Posts
Just a heads up that in addition to the bluetec extended warranty, there is a “lemon law” clause. If the vehicle isn’t driveable for 30 days during the first 18 months after the emissions update, then Mercedes must repurchase your car. For example if the dealer couldn’t get you scheduled or you have to wait for the part.
 
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