Info on 2011 Hyundai Santa Fe slams into lower gear while driving

whydoit

We have a 2011 Santa Fe Limited 4-cyl. While driving normally (not accelerating/decelerating), a very loud "bang" as though you've hit something with the bottom of the car, and the whole car feels the event, the car slams going into a lower gear. It then won't shift back up. This has happened both at city speeds (30-40mph) and highway (60-70 mph). After the loud bang and jolt, the tach is running at 3500rpms (depending on speed).

There are no alarms/alerts on dash, no indication that any code has been saved by the computer. My son works at Auto Zone, he did not see a code.

You can stop, leave the car running, take off, and the car will stop shifting before high, running to 3000+ RPM. However, if you stop, turn the car off for a few seconds (15-30), then restart, it drives normally. It's very intermittent, once happened 2x in one day only a 30 mins apart, but the rest of the time it's days or weeks between events.

I've searched the Hyundai forum, didn't find anything referring to this. Anyone else had the problem, or can point me to a discussion on it?

Mr_Shiftright

Sounds to me like (possibly) a torque converter issue of some sort, or maybe shift solenoids. Autozone might not be able to read the kind of code that's stored in the TCM.

There is a dealer Technical Service Bulletin on this symptom. A TSB is not a recall, it's a dealer advisory, so this doesn't mean it's free necessarily.

Here's the info on the TSB. The "GDS" referred to is the dealer's computer, which can see and do things a code reader can't.

NUMBER
13-AT-009
DATE
MAY 2013
MODEL
Tucson (LM), Santa Fe
(CM/AN/NC), Sonata (YF/YF
HEV), Elantra (UD/MD/GD/JK),
Accent (RB), Azera (TG/HG),
Veloster Turbo (FS)
SUBJECT:
AUTOMATIC TRANSAXLE HARSH AND/OR DELAYED SHIFT - GDS ANALYSIS

whydoit

I appreciate your response. I tried to reply before, looks like it failed, so sorry for delay on my part. The info regarding codes Auto Zone could not read is really helpful.

I will definitely take this under advisement.

I only found a couple places about this, and only this short description, but nothing on Hyundai's website.

My only question is this refers to - as do most of the transmission posts or TSB's - a delay or harsh shift, usually in the context of going through the gears. In our case, this severe shift is a downshift only, and after the car has reached a cruising speed, and is no longer accelerating. It has been on flat ground, so no downshift was needed.

So it would seem that your thoughts might be spot on, but the TSB's don't match exactly (this or others I could find). Either way, you've been very helpful, and we'll see if a dealer can find something.

Thanks much!