2012 3.8 8-speed Auto Transmission Shifting Weird

[Breery]

Hey Guys and Gals, I've got a 2012 3.8 with the 8-speed auto trans. It's got 113k miles on it and I've owned it for about a year (had 107k when I bought it).

I'm having some intermittent but noticeable transmission shifting weirdness. I'm getting occasional bad shifts from 2nd to 3rd and also 4th to 5th.

2 --> 3 : average disengagement of 2nd but grabs 3rd too early while revs are too high (typically only a could hundred RPM drop) and slams into gear. Not overly violent but more of a jerk than a typical shift.
4 --> 5 : slow disengagement of 4th, sits in neutral for around a second, revs climb while in neutral (sometimes as much as 2k RPM increase), slow engagement of 5th. Because of the slow disengagement and re-engagement of both gears I wouldn't call this a slam shift because there's never a big jerk, but power delivery is lost to the wheels for a couple seconds while all this is going on. Strange feeling.

I haven't been able to nail down a consistent set of conditions to reliably replicate the problem but I'd say in general this is happening more when the car is up to full operating temperature. But even then, it's not all the time.

I also did a scan of the computer with an OBD scanner and did receive a code P0955 which comes back as auto shift manual mode circuit fault. However, I have no problems using the manual shift mode, it works fine (though the odd shifting does still happen sometimes in manual mode).

Anyway, I have limited experience troubleshooting automatic transmissions and any insight would be appreciated. Thanks!

P.S. I've purchased "Niteo Motor Medic M3616 Trans Medic Automatic Transmission Treatment & Shift Improver" from Amazon with the intention of adding it to the trans fluid. Figured this couldn't hurt, but please let me know if this is a bad idea. As far as I know the trans fluid has never been changed since Hyundai claims this never needs to be done.

 

[Mark_888]

P.S. I've purchased "Niteo Motor Medic M3616 Trans Medic Automatic Transmission Treatment & Shift Improver" from Amazon with the intention of adding it to the trans fluid. Figured this couldn't hurt, but please let me know if this is a bad idea. As far as I know the trans fluid has never been changed since Hyundai claims this never needs to be done.

Yes it will hurt, so don't do it. Return it. The Genesis transmissions only take a certain kind of synthetic transmission fluid, and even the wrong synthetic fluid will ruin the transmission.

2012 was the first year of the Hyundai 8-speed transmission, and a lot of the early ones had problems that required Hyundai to replace them under warranty. This has been discussed on many threads in this forum. There are very few people who fix those kind of transmissions, and even Hyundai dealers will only replace them, not repair them.

I would start looking around junkyards (including online ones) for a transmission to replace yours if you want to keep your car much longer, or continue manual shifting. You will want a transmission from a 3.8 Genesis from 2013-2014 model years. Some late 2012 ones maybe OK, but I don't know which build date that is.

A brand new transmission is about $5300 with online discount, plus shipping, plus installation at a dealer.

 

[Breery]

Yes it will hurt, so don't do it. Return it. The Genesis transmissions only take a certain kind of synthetic transmission fluid, and even the wrong synthetic fluid will ruin the transmission.

Good to know, I'll send it back. I was guessing that the transmission would eventually end up needing to be replaced but I certainly don't want to accelerate the problem.

It's unfortunate that failure seems common yet Hyundai hasn't figured out a way to repair them without total replacement. It sounds like the transmissions from 2013-2014 are direct replacements without any modification?

I appreciate all the information. This is pretty crappy news to hear considering I just bought this car less than a year ago.

 

[Mark_888]

Good to know, I'll send it back. I was guessing that the transmission would eventually end up needing to be replaced but I certainly don't want to accelerate the problem.

It's unfortunate that failure seems common yet Hyundai hasn't figured out a way to repair them without total replacement. It sounds like the transmissions from 2013-2014 are direct replacements without any modification?

I appreciate all the information. This is pretty crappy news to hear considering I just bought this car less than a year ago.

I checked the parts catalog and 2012 - 2014 3.8 used the same transmission. Go to this site and scroll down to "This Part Also Fits"
Transmission - Hyundai (45000-4F070) | hyundaiparts

It is possible that Hyundai Motor America can fix them, but repairing transmissions is usually beyond the capability of dealers these days. That not just for Hyundai, but for just about all other brands (who sometimes use transmission not even made by them, but made by companies like ZF or Aisin).

Part of that is the complexity of modern transmissions and part of it is that they are generally more reliable and most techs don't have enough experience.

 

[hawkeye99]

Just curious of what the build date of your car is?

 

[Breery]

Just curious of what the build date of your car is?

March 10, 2012 so I'm assuming I have the early version of the transmission.

 

[hawkeye99]

I'm thinking late in the production year. They would be gearing up for 2013 model's soon. But I'm note sure. Mine was built in May of 2012. No issues yet but only 42000 kms.

 

[Mark_888]

March 10, 2012 so I'm assuming I have the early version of the transmission.

I don't think anyone knows when it got fixed. The symptoms you are having seem to be like the ones that got replaced under warranty. I think the amount of time they last (even if defective) depends on how hard people drive them.

Model years 2013 - 2018 (with basically the same transmission) have been very reliable.

 

[dougmcp]

I would do a simple drain and refill of your transmission. You could have anything from low fluid to slightly plugged solenoids to junk in the pan. The small cost of this should determine your next move.
It's a simple drain and fill function and should take 5 or 6 qts, use the correct Hyundai Genuine ATF SP-IV-RR fluid without any additives (magic formulas).

 

[EdP]

I would do a simple drain and refill of your transmission. You could have anything from low fluid to slightly plugged solenoids to junk in the pan. The small cost of this should determine your next move.

That makes a lot of sense. I had a trans suddenly"fixed" by having it drained and the same fluid put back at a trans shop. If that cures it, great, if not, my next step would be to trade it in.

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[where'dthat5.0go]

I have a 2012 5.0 R Spec and I'm having the same issue. It started on Father's Day, so only a couple of weeks ago.
Everything was fine until the alternator died while I was driving , which also killed the battery. The battery light came on and by the time I reached my destination, which was about 10 mins after I noticed the warning light, nearly all of the electrical system was shutting down.
$800 later for a new alternator and (monster) battery, and the tranny is shifting really hard from 3-4 and 4-5.
Could the computer have been affected and is now causing the transmission issues?
Currently there are just under 93K miles. Hopefully its still under the power train warranty.

 

[Mark_888]

Currently there are just under 93K miles. Hopefully its still under the power train warranty.

Assuming you can replicate the shifting problem for the dealer, take it in ASAP. Take the service advisor for a ride if they claim they can't replicate it.

If you are the original owner, or purchased it as a CPO, the transmission is under warranty.

 

[where'dthat5.0go]

Thanks for the response and advice. I'll update when I have more.

 

[Breery]

I would do a simple drain and refill of your transmission. You could have anything from low fluid to slightly plugged solenoids to junk in the pan. The small cost of this should determine your next move.

I was thinking about doing this but I've heard before that this could make symptoms worse on a transmission with higher mileage. Although that was some time ago and may not apply to newer transmissions. Either way it's worth a shot and seems simple enough that I might try to do it myself. I assume I can just get the fluid at the Hyundai dealership parts department.

That makes a lot of sense. I had a trans suddenly"fixed" by having it drained and the same fluid put back at a trans shop. If that cures it, great, if not, my next step would be to trade it in.

Trade in is exactly what I had in mind if I can't find a fix. I don't want to deal with replacing this transmission after having the car for such a short time.

 

[Breery]

I went ahead and bought Castrol Transmax Full Synthetic Multi-Vehicle transmission fluid from Advance Auto Parts since they said it’s an exact match for the vehicle. So I’ll do the drain/fill sometime this weekend. Hopefully it makes a difference, but I’ll keep you guys updated. Thanks for all the help so far.

 

[dougmcp]

It's your transmission and ultimately your decision as to what transmission fluid you use but I wouldn't put anything in mine but Hyundai Genuine ATF SP-IV-RR. It's available online or at a Hyundai or Kia Dealer.
Here is a statement directly from a Castrol tech:
Castrol cannot guarantee compatibility with competitive fluids as we do not know their proprietary formula, therefore we recommend a complete drain of the transmission and re-fill with Castrol Transmax Import Multi-Vehicle ATF. This should include draining the torque converter which holds about one-half of the ATF volume -- dropping the pan will not cause the torque converter to drain. You may find directions for draining the torque converter online, or may wish to have this service performed for you by a service facility.

 

[Breery]

Understood. I looked on three different Hyundai parts sites and I couldn't find fluid on any of them. So I guess my only option is going to the dealer? Any idea what they charge for the fluid?

 

[dougmcp]

I haven't priced it lately but the KIA dealer is usually much cheaper. If memory serves it's about $12-$15 a quart and you should need 5 or 6 to do a simple drain and fill.
A quick search yielded:
1) https://www.amazon.com/Hyundai-00232-19052-SP-IV-RR-Automatic-Transmission/dp/B00AKYOIUE
2) 00232-19052 - Genuine Hyundai ATF SP-IV-REAR

 

[Breery]

Much appreciated. I'll try and pick some up tomorrow and take back the Castrol. I even searched Amazon and I swear that didn't show up, but I also could just be blind. Either way, you've been very helpful. Better safe than sorry with the Hyundai fluid.

 

[bigpapainscotia]

I'm having the same problem with my 2012 sedan, it will come for two to three days then will be gone for a month. I think I will get the tranny flushed out soon.