MajorCommonTransmission

Mercedes-Benz GLS: 9G-Tronic (725.0) Harsh Shifts, Shudder and Limp Mode (X166 GL350 / GLS)

9G-Tronic (725.0) Harsh Shifts, Shudder and Limp Mode (X166 GL350 / GLS) is a common transmission fault on the Mercedes-Benz GLS on the 2017–2019 cars, and we rate it major. Putting it right costs $300 to $6,500 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 10 documented faults on the Mercedes-Benz GLS.

Vehicle: Mercedes-Benz GLS
Only on: AMG
Years: 2017–2019
Gearbox: auto
System: Transmission

This page covers the Mercedes-Benz GLS as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Mercedes-Benz GLS faults10 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Mechatronic / valve body yet. We would rather show none than show a picture of a different part.

What goes wrong

From around 2015 the GL350 BlueTEC, and every GLS350d and GLS500 after the 2016 facelift, use the 9G-Tronic 725.0 nine-speed automatic instead of the 7G-Tronic (the AMG 63 models kept a seven-speed). Owners report harsh or clunky low-speed shifts, hunting between gears, shudder when moving off, and occasional limp mode stuck in one gear. Mercedes bulletin LI27.00-P-060741 covers rough shifting, shudder and limp-home on the 725.0 and prescribes an oil level check, valve flushing, software updates and adaptation. Most cases are fixed with software and a correct oil level, but some need valve body or electrical work. There is no recall or extended warranty.

What you would notice

Clunk or jolt on low-speed shifts, especially when slowing to a stop
Shudder when pulling away
Gear hunting on hills or in traffic
Transmission warning or limp mode stuck in one gear
Delay when selecting Drive or Reverse

How to check it

Where to look. Automatic transmission behind the engine, with the control unit and valve body inside the transmission

On the test drive include stop-start traffic and a gentle slow-down to a stop, and feel for clunks as it changes down. Pull away gently and then firmly and feel for shudder. Shift from Park to Reverse to Drive and note any delay or thump. Watch for transmission warnings on the dash. Ask whether the gearbox software has been updated and whether the transmission oil has ever been changed. If a workshop inspection is possible: have a Mercedes specialist read the transmission control unit for fault codes, check the software level against the latest release, check the oil level at the correct temperature, and review adaptation values.

Parts involved: Mechatronic / valve body.

What it costs to put right

$300 to $6,500 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“Has the transmission software been updated at a Mercedes dealer?”
“Has the transmission oil and filter been changed, and when?”
“Has it ever gone into limp mode or shown a gearbox warning?”

Now check the Mercedes-Benz GLS you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

Mercedes-Benz TSB LI27.00-P-060741 'Shifting complaints and transmission fault codes in vehicles with transmission 725.0' (NHTSA MC-10179949)
Au7o known issues: 2017 Mercedes-Benz GLS, 9G-Tronic harsh shift
Mercedes-Benz TSB LI49.20-P-056353 validity list showing model 166 OM642 with transmission 725.031 (9G-Tronic on the OM642 model 166)

Mercedes-Benz GLS buyer questions

Is 9g-tronic (725.0) harsh shifts, shudder and limp mode (x166 gl350 / gls) serious on a Mercedes-Benz GLS?

We rate it major and common on the Mercedes-Benz GLS. From around 2015 the GL350 BlueTEC, and every GLS350d and GLS500 after the 2016 facelift, use the 9G-Tronic 725.0 nine-speed automatic instead of the 7G-Tronic (the AMG 63 models kept a seven-speed). Owners report harsh or clunky low-speed shifts, hunting between gears, shudder when moving off, and occasional limp mode stuck in one gear. Mercedes bulletin LI27.00-P-060741 covers rough shifting, shudder and limp-home on the 725.0 and prescribes an oil level check, valve flushing, software updates and adaptation. Most cases are fixed with software and a correct oil level, but some need valve body or electrical work. There is no recall or extended warranty.

How much does it cost to fix on a Mercedes-Benz GLS?

$300 to $6,500 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Mercedes-Benz GLS years are affected?

Our research records this fault on the 2017–2019 Mercedes-Benz GLS. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.