Apple hardware test has detected an error 4mem 9 40000000:0x8306e618

As was stated, one DIMM died on you. Not sure which one, but you can try removing just one (to see if that's the bad one) and it should be able to run just fine until you can get a replacement. Of course if you remove the good one then put that back in and take out the bad one. Theoretically it uses the memories as matched pairs, but it should be able to operate on just a single DIMM.

You have a defective memory card in that MBP

Grant Bennet-Alder wrote:

The memory test that runs at startup is very coarse, and only runs for a few seconds . It will not find every RAM error by any stretch of the imagination. About all it can find in that time is a solidly-stuck bit somewhere.

If it won't boot due to an error, then I'd think removing the bad one would probably take care of it until a replacement is installed. Right now the OP isn't getting to actual booting, so I was thinking of that being solved more than running a memory test at startup. Could be some gross error like the onboard controller. And if it's something more severe like a damaged socket, then nothing would fix it save a very expensive repair.

Good luck with it. You'll know if you pulled out the right one if it boots. There's a power-on self test every time you boot, and that runs a basic memory test like what AHT does.

What we all write will be here for a long time. Other Readers may later find posts here by searching -- sometimes even into the middle of a thread without seeing the progression of ideas.

I did not want to leave ANYONE with the concept that most memory problems can be effectively detected by the Power-On Self Test, or even by Apple Hardware test. Your saying that the Power-On Self test is "just like what AHT runs" is too broad in general, even if it applies perfectly in this one specific case.

When getaroomtest says this problem is precluding boot-up, then removing the Bad DIMM should provide relief, and if not, removing the other one instead should provide that relief. I agree that it may be as simple in this case as using the Power On Self Test to make that determination.

I am asking you to think a bit more about what you write, and the much wider audience you are actually addressing by posting in these very public forums. We have far more "lurkers" than responders even as these threads are active, and many, many more Readers when you and I and the Original Poster have forgotten all about them.

The memory test that runs at startup is very coarse, and only runs for a few seconds . It will not find every RAM error by any stretch of the imagination. About all it can find in that time is a solidly-stuck bit somewhere.

Your response was perfectly appropriate if it were a one-to-one email between you and the original Poster.

As I started composing this writing, there are over 42 views on this thread, and only 8 postings. You are actually addressing a much wider audience than it seems.

I am just trying to get you to think about everyone who will read your words. I am suggesting you may need to be a little more general in what you say, and how you say it. It is not a big deal. I am not attacking you. Your posts to date are quickly becoming important additions here.

Grant Bennet-Alder wrote:

What we all write will be here for a long time. Other Readers may later find posts here by searching -- sometimes even into the middle of a thread without seeing the progression of ideas.

I did not want to leave ANYONE with the concept that most memory problems can be effectively detected by the Power-On Self Test, or even by Apple Hardware test. Your saying that the Power-On Self test is "just like what AHT runs" is too broad in general, even if it applies perfectly in this one specific case.

When getaroomtest says this problem is precluding boot-up, then removing the Bad DIMM should provide relief, and if not, removing the other one instead should provide that relief. I agree that it may be as simple in this case as using the Power On Self Test to make that determination.

I am asking you to think a bit more about what you write, and the much wider audience you are actually addressing by posting in these very public forums. We have far more "lurkers" than responders even as these threads are active, and many, many more Readers when you and I and the Original Poster have forgotten all about them.

I was responding to the original poster, and I gave accurate information in simple language that the average person should be able to understand. All of what I posted applied to the OP's situation. I was hinting that there seemed to be a memory error uncovered by AHT, and whatever it was probably wasn't getting past the memory tests done in power on self test. It was wholly accurate to say that POST runs a "basic memory test". If anyone is lurking and looking at this forum for advice, all I can say is to read answers carefully. If anyone has a memory error that's not uncovered by POST, they'll eventually see it manifest as a freeze or kernel panic, at which point Apple Hardware Test should be run.

My suggestion was to test the DIMMs one at a time or test the sockets one at a time, which nobody else had suggested. I understand that some people are under the impression that it won't work if both sockets aren't populated.