MajorCommonTransmission

Mercedes-Benz S-Class: 722.6 5G-Tronic conductor plate failure and leaking 13-pin connector (W220)

722.6 5G-Tronic conductor plate failure and leaking 13-pin connector (W220) is a common transmission fault on the Mercedes-Benz S-Class on the 2000–2006 cars, and we rate it major. Putting it right costs ≈A$640 to ≈A$2,300 at independent workshop rates, shown as an approximate guide in Australian dollars. 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 22 documented faults on the Mercedes-Benz S-Class.

Vehicle: Mercedes-Benz S-Class
Years: 2000–2006
Gearbox: auto
System: Transmission

This page covers the Mercedes-Benz S-Class 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 S-Class faults22 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

The W220's 722.6 five-speed automatic is mechanically strong, but its electronic conductor plate (inside the valve body) is a documented weak point: failure causes rough or strange shifting, loss of gear position display, and the classic limp-home mode stuck in 2nd gear. The 13-pin electrical connector also leaks transmission fluid up the loom toward the control module, which can destroy the TCU if ignored. Replacement conductor plates come pre-programmed and the repair is straightforward for a competent independent, especially done with a fluid and filter service.

What you would notice

Stuck in limp mode / 2nd gear only
Harsh or erratic shifting
Gear display blank in the cluster
Oil residue around the transmission connector

How to check it

Where to look. Automatic transmission under the centre of the car; 13-pin connector on the transmission housing

On the test drive from cold, work through gentle and firm acceleration and watch for flaring, thumps or a sudden drop to limp mode. Check the transmission connector area for fluid weepage and ask when the transmission fluid was last changed - 'sealed for life' means never, which is a red flag at this age.

Parts involved: Mechatronic / valve body.

What it costs to put right

≈A$640 to ≈A$2,300 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, 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 conductor plate or valve body ever been replaced?”
“When was the transmission fluid and filter last changed?”
“Has it ever gone into limp mode?”

Now check the Mercedes-Benz S-Class 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 still has money owing on it, has been written off or reported stolen, what kms it showed in past sale ads, whether it has had accident repair claims and what it is worth today. That comes from the official records for that plate. Enter the plate and its state for the A$17.90 Vehicle Check, or the full history from A$24.99.

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.

The Autopian 'Here's What A Conductor Plate Is And Why It Kills So Many Mercedes'
YOUCANIC 722.6 valve body / conductor plate replacement guide
Benzworld W220 thread 'Mercedes Transmission gurus, please help!'

Mercedes-Benz S-Class buyer questions

Is 722.6 5g-tronic conductor plate failure and leaking 13-pin connector (w220) serious on a Mercedes-Benz S-Class?

We rate it major and common on the Mercedes-Benz S-Class. The W220's 722.6 five-speed automatic is mechanically strong, but its electronic conductor plate (inside the valve body) is a documented weak point: failure causes rough or strange shifting, loss of gear position display, and the classic limp-home mode stuck in 2nd gear. The 13-pin electrical connector also leaks transmission fluid up the loom toward the control module, which can destroy the TCU if ignored. Replacement conductor plates come pre-programmed and the repair is straightforward for a competent independent, especially done with a fluid and filter service.

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

≈A$640 to ≈A$2,300 at independent workshop rates, shown as an approximate guide in Australian dollars. 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 S-Class years are affected?

Our research records this fault on the 2000–2006 Mercedes-Benz S-Class. 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.