Early Model S electric-drive units

Early Model S electric-drive units

I read that "Survey data collected by Plug-In America from current early-model Tesla Model S owners has predicted that up to two-thirds of early model electric-drive units may fail by 60,000 miles. If their predictions are even remotely accurate, that’s bad news."

First, what is the electric drive unit? I think it is the motor, inverter, and gearbox.

What is an "early model" as stated above?

My car is a P85D built in December of 2014 - is it an early model?

After 50K miles, owner is responsible for this large replacement cost of what - $15K? Or, does the 8-year unlimited mile warranty kick in here?

PBEndo | August 17, 2016

8-year unlimited covers it

Mathew98 | August 17, 2016

Failed as in completely stop cranking to propel the car or just some annoying milling sound (not as loud as an ICE)?

Early as in 2012, 2013, and perhaps parts of 2014. Say VIN unde 50K? The bearing were switched to ceramic ones to eliminate the milling sound.

stevenmaifert | August 17, 2016

Very few "early" drive units have actually failed, leaving the driver stranded by the side of the road. However, very many "early" drive units have developed a variety of noises leading Tesla to do a precautionary replacement. Mine was one of them at 20K miles. It depends on how you define "fail", but there is a very good chance two-thirds of early model electric-drive units may get replaced by 60K miles.

Silver2K | August 17, 2016

The newer DUs have the spline autogreasing technology and the earlier DUs do not as per Elon. I don't know if that's been rectified on older DUs, but my DU was replacement recently because of spline making clunking noise. This is the 2nd DU in my car's history @34k miles

Silver2K | August 17, 2016

Replaced..... thanks Samsung!

Mathew98 | August 17, 2016

Your bigger screen does not resolve your auto-incorrect impotence...

freeewilly | August 17, 2016

I have a late 2013 model MS. If my DU failed today, will Tesla replace with the same kind of DU or ceramic ones

Silver2K | August 17, 2016


Made it worse! But the measurements are done easier now.


They will give you a rebuilt and corrected DU

Innkeep | August 17, 2016

My 2014 S 85 developed a slight sound at 7000 mi that seems to go away at 30 mph. At 2 year check up the mechanic said that they now accept a certain amount of motor noise as the car ages. Although I suspect it is the "dreaded" milling sound I decided not to escalate the complaint because I know if it worsens they will make it right, and because it sounds like a rocket ship going into warp speed to me.

EdwardG.NO2CO2 | August 17, 2016

@flight505, let me summarize what has been said, I have experienced, and what I have read since 2013 ( my first Tesla). Very few drive units have actually failed but two types of noises have developed that led to Tesla taking action.
The milling sound seems to be caused by reduction gear or motor bearings when unexpected pitting occurred caused by electrical flux interference of steel to steel bearings. Once the cause was discovered it was resolved but introducing ceramic (non conducting) bearings.
The clunking seemed to be a symptom of spline wear caused by lubrication failure and high stress. Changing lubrication I believe has resolve that as well.

My drive unit change was free and at the time I was told it was covered under the 8 year warranty.
My Sept. 2014 Tesla shows no sign of either issue and in fact has been totally free of problems.
Hope this gives you some level of comfort.

Tropopause | August 17, 2016


The battery and drive unit are covered for 8 years but I have read some posts here stating that Tesla does not consider the half-axles part of the drive unit and thus will only be covered under the bumper-to-bumper 4yr/50k mile warranty. The verbiage is specific to say "drive unit" not "drive train" so I am concerned about this aspect. However, my main concerns for battery and drive unit are alleviated thanks to the 8 years warranty.

AmpedRealtor | August 17, 2016

I have had four drive unit replacements, all for noise. You can determine for yourself whether or not that constitutes a failure.

Silver2K | August 17, 2016


when was the last one replaced?

flight505 | August 17, 2016

My P85D built 12/19/14 - a later version so no worries, I gather

negarholger | August 17, 2016

My noise issue ("the hum") at 18k miles was very temperature dependent... in the seventies barely noticeable, but annoying with temperatures in the nineties. @AR has an early 2013 car like mine and lives in AZ... that might explain some of his multiple DU replacements.

cweber | August 17, 2016

Excellent timing for this post. My drive unit was replaced today (took only few hours) at Denver SC. March 2014 S85 with 52K miles and very audible milling sound which began about 10,000 miles back. No "failure" of the unit occurred.

ssarker | August 17, 2016

April 2013 60 kWh Model S. First replacement at around 15k miles summer 2014 for >65 mph "hum". Second replacement in May 2016 at my 50k service for the "milling" sound. I was told that the driveuit would fall under the 8 year/ 125k mile battery warranty.

justinmk3 | August 17, 2016

PBendo said it first, has it right. "8-year unlimited covers it" Do you see how calloused we've become? We are so used to the big Auto Companies being crappy, (like pulling teeth just to claim your rightful warranty) That its like we don't believe Tesla or something. Trust me, they stand by their warranty, and then some. My advice, stop worrying and start enjoying your Tesla. :D

ktjones | August 17, 2016

My sept, 2014 model s85 with a serial number of 56xxx just had its drive unit replaced at 29,000 miles for loud milling sound. All is well again!

sklancha | August 17, 2016

What adds to the stress to the casual reader is the verbiage of the article. 'Up to 2/3rd of drive units will fail' in the ICE world, they would never consider replacing an engine unless it was an epic failure. Tesla's approach to resolving milling sound is just something they cannot wrap the head around.

It would be interesting to know how many early models truly did have drive unit failure, and how that compares to first year models of other cars.

The flying hippie | August 18, 2016

So when exactly did Tesla start putting ceramic bearings in the drive units? How would one know? Is there a serial number like the battery pack? My December 2014 S85 has a very faint high pitch sound audible at low speeds when accelerating or in regen. I assume it's there at higher speeds too but road noise drowns it out. Is that the dreaded milling noise?

bak_phy | August 18, 2016

The drive unit on my 2014 P85 was replaced at my last annual despite me not having had any issues with it.

justinmk3 | August 18, 2016

FLyinghippie, I heard around rev q the issue has been resolved.

keydiver | August 18, 2016

When my 70D was being manufactured in September 2015 (VIN 999xx), Elon revealed that they had been shipping the "Million Mile" drive unit with better lubrication for several months. No worries here.

jbunn | August 18, 2016

What Plug In America might not have taken into consideration is that Tesla kept a lot of those drives for destructive testing and failure analysis instead of just replacing the bearings or shims.

This is a good thing.

I have a 2013 S and the instrument cluster failed last month. I asked the SA what happened to the old part. He said, it's going to engineering, and they are going to take it apart.

That's how you close the loop on failures...

mybluetesla | August 19, 2016

My S85 was built in 09/2014, I don't really consider it an "early" model but I did get my DU replaced due to milling noise at almost 36k on the odometer earlier this year. I lived with the noise for maybe 15k miles before I decided it was time to have it looked into. I got a "Q" version replacement.

I think the DU issue is largely a thing of the past at this point, but occasionally I still read about complaints.

While simplistically it's easy to relate the DU as an equivalent to an engine in a gas car, in practice a DU much easier to service and a swap only takes a few hours. Somewhat trivial in the grand scheme of things.

flight505 | August 19, 2016

a very faint high pitch sound audible at low speeds when accelerating or in regen

I think this sound is normal. How could an electric motor be without some noise?

Still no answer for when or what serial # Tesla switched to the ceramic bearings or the better drive unit.

murraypetera | August 19, 2016

I have early model 40 and have 71k miles no drive train issues yet...

hpjtv | November 12, 2016

Getting my drive unit replaced soon. At 72k km, was making noise around 60k km. Have a Dec 2014 Model S 85. Just wondering if anyone has ever asked to upgrade their 85 to a P85 DU and pay the difference since they need to get a DU replaced anyways.

nick-r | November 13, 2016

I have had the drive unit on my 2013 P85+ replaced three times.

The first time was due to an actual failure. I was pulling out of a parking lot into traffic. I felt a really powerful jolt from the back of the car, almost like I had just hit a curb doing about 30 miles an hour. I was stopped and had just started to accelerate when this happened. The car then drifted into traffic. The accelerator pedal wouldn't work, but I was able to steer and coast to a safe stop. I PO'd a bunch of people on the road though.

The second and third time the drive unit was replaced due to grinding noise issues.

Silver2K | November 13, 2016

I have mine replaced due to a clunking noise when I took off from a stop (easy or hard). The spline wasn't being greased properly(?), but the new units have an automatic greaser.

the new units for our cars @nick-r with the code Q in the part number is suppose to be the best units. I have the P coded unit in my p85+ and so far no issues and it's completely silent!

The flying hippie | November 13, 2016

Huh, I had that metal on metal clunk but they just re greased the spline and sent me on my way. Still getting a clunk between power and regen like there's a bit of loose in the spline. Now I'm getting a low milling noise below 20 km/h. Turning the radio on fixes it for now but I'm hoping they swap in a Q unit at the next scheduled maintenance. I'm on the original Dec 2014 S85 DU. I'm guessing ceramic bearings started making their appearance shortly after that.
Silver, are you sure the P coded unit isn't the latest version for the P85? Seems like the S85's have been getting the Q units. I was under the impression they were the same except for the inverter. I could be wrong.

sundoc | November 13, 2016


My P85D was built just before yours 11/24/14 and I'm now at 45,000ish KM... I've developed that milling sound for the past few months, it was actually my neighbour mentioning he hears me coming which made me realize the sound was even there.

Launches the same as always and performance hasn't declined at all... just has this milling/buzzing noise at low KWh. I've discussed it with the Service Centre and the plans is to 'watch and wait' but it has been slowly getting louder. I'll likely let it go until my summer tire swap and then discuss the matter again, unless it gets significantly louder in the interim.

EESROCK | November 13, 2016

Mine is P85 Mar. 2013. Our original drive unit got replaced in February this year because of the hum (we started noticing it several months before that but at the time, the SC said the noise was still within spec). Then it got replaced a couple of months ago due to the clunking noise.

dborn | November 13, 2016

@ The flying hippie: I had that identical clunking noise you describe in an October S85, 2014 with 27500 km on the clock. They re packed the hubs with great, replaced and retorqueing the hub nuts and washers, and that has fixed the problem.

dborn | November 13, 2016

Grease not great

Silver2K | November 13, 2016

Soaring hippie

You're correct, Q is for non-performance. I knew this because I thought I got the wrong drive unit a few months ago, because it felt weak :).

The flying hippie | November 13, 2016

Did you have a Ludicrous loaner?

Silver2K | November 13, 2016


My car's pedal is tighter, that's why I felt a difference. I would put the same amount of pressure on the pedal and the p85 was jumping like crazy. the other difference is the + suspension is tighter and the p85 with 19's felt softer and made the car seem faster

Elec Spd | February 22, 2017

My 2013 P85 just had the second drive unit replacement at 87K miles. First one was clunking at 45K, second was milling.

Qwiksilver | February 24, 2017

You will get a refurbished (up to or exceeding the specs of your original unit)