Got a diagnostic saying my battery coolant heater may need to be replaced after i got notification on dash that said “ service required, may not restart” i have my service appointment tomorrow has anyone ever gone in and it had not to be replaced and it was another issue? I never received the same message again the rest of the day.
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Battery Coolant Heater
- Thread starter brianhernandez
- Start date
So my 2016 model S gave the error code Bms_w035 code just as I arrived and parked at a supercharger. Since I was navigating to the supercharger, it said it was preconditionping for faster charging. the car did supercharge at 100+kw so the battery was warm. the First message triggered a service required message. When I started the car after supercharging, it threw the additional codes bms_w172 and bms_u008. The dreaded ”limp mode” and “car may not restart” mesages. I scheduled service the next day and got an appointment for 3 weeks later. I Drove the car in limp mode a few times and did a power down restart but limp mode and may not restart remained. It looked like they did a remote diagnosis when they scheduled the appointment and they predicted the expected battery heater needs replacing and quoted $658 to fix it since I am out of warranty. I dropped the car off and got a model 3 performance loaner. It took them another week to actually look at the car. When they cleared the limp/may not restart codes it no longer reported any trouble. They ran diagnostics and found nothing. They called and asked permission to do additional debug for a 1 hour service fee. I reluctantly said ok, and they did additional testing and thermal cycling. They couldn’t find any problem. In the end quite a big hassle for what seemed in my case to be a software glitch. In the end I wished I had gotten them to clear the limp code remotely and just seen if the code for the battery heater would reappear. YMMV.
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I have my car in the shop today because i suspect the battery heater is dead, or at least is not functioning. Tesla has ordered the part and given me a completion date of two days from now. In contrast to the post above, I never got any warning messages of any sort. it just would not charge if the battery is cold. I did some tests and convinced myself that the battery was not getting heated if i navigate to a Supercharger, as it should. Nor would it get heated if i tried to charge a cold battery on my Tesla Wall Connector. i have had the car 6 years so i am familiar with the expected winter behavior. But curious that i got no messages or warnings.
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After another visit to a supercharger I got the bms_w035 and limp mode again. So back to the service center. This time, after the car sitting there for a few days before being looked at, they replaced the battery heater and all is good again. I had them give me the old heater, I’m thinking about taking it apart to see what went wrong.
Based on using TM-Spy to monitor the battery heater temperatures, it seemed that the old one worked somewhat, but not anywhere as good as the replacement.
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My car has also been in the shop for several days, with no result yet. When I stopped by to check, I was told that they had not yet run the diagnostics on my car, owing to other work in the shop and a lack of staff due to Covid-19. So, the indication that they had ordered the heater was simply to verify it is in stock, if needed. So, I guess I need to "stay tuned...."
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Got my car back today. Tesla replaced both the battery coolant heater and one of the coolant pumps. Today was mild (temps in the 40s) so I am not yet sure if these changes fixed the problem, but I hope so. The car battery warmed up quickly and I got back full regen after only a couple of short local trips, so that was promising. Very cold weather expected this weekend, so that could be a good test.
By the way, the service writer said the work would have cost about $1600-1800 if I did not have the Extended Service Plan, so I was glad I did not have to pay the full cost!
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Had the same codes thrown when in line at a Supercharger in Las Vegas (prepping for the 300 mile drive home). Exact same sequence. In line received BMS _w035 'Vehicle may not restart (Service is required),' which promptly went away and seemed fine. Once I plugged in, received BMS _w172 'Vehicle may not restart (Service is required),' and BMS _u008 'Acceleration and top speed reduced (Performance may be restored on next drive).'
Found this thread while charging, and figured we'd see if it goes away. After restarting, the only powerband useable was under 75Kw, above showed the yellow dash lines, and below 0 showed the same. There was no regen breaking at all. As a result, wh/mi were much higher than usual. I didn't know if it was safe to drive all the way home (as I mentioned, ~300 miles), plus at this rate would have to stop and supercharge to 100% multiple times.
Made an appointment through the app, but soonest was 6 days away, so just drove to the service center. They performed a diag and confirmed it was the 'battery electric coolant heater.' Car is out of warranty so did have to pay out of pocket, but they got us in at 4PM and had the car ready the next day by noon. Big shout out to the Las Vegas SC on Sahara. They also had a MX loaner for us (we had 6 people in our X) and were very great with everything.
So far so good. Just wanted to share the experience confirming what others have said in the post about these codes and the battery coolant heater.
Found this thread while charging, and figured we'd see if it goes away. After restarting, the only powerband useable was under 75Kw, above showed the yellow dash lines, and below 0 showed the same. There was no regen breaking at all. As a result, wh/mi were much higher than usual. I didn't know if it was safe to drive all the way home (as I mentioned, ~300 miles), plus at this rate would have to stop and supercharge to 100% multiple times.
Made an appointment through the app, but soonest was 6 days away, so just drove to the service center. They performed a diag and confirmed it was the 'battery electric coolant heater.' Car is out of warranty so did have to pay out of pocket, but they got us in at 4PM and had the car ready the next day by noon. Big shout out to the Las Vegas SC on Sahara. They also had a MX loaner for us (we had 6 people in our X) and were very great with everything.
So far so good. Just wanted to share the experience confirming what others have said in the post about these codes and the battery coolant heater.
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2016 Model S 90 - mileage 30K miles - got the same message of death "Car May Not Start" was in October. Made appointment on app - diagnosed as coolant heater failure, $1600.
Only had the car for about a month.
Love the car, but definitely took the wind out of my sails. Is this common? Don't know what else to expect?
Only had the car for about a month.
Love the car, but definitely took the wind out of my sails. Is this common? Don't know what else to expect?
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My 2015 Model S battery coolant heater was replaced at about 65,000 miles, after more than 6 years. I assume it only failed a short time before that, but I do not know if they deteriorate over time or just fail abruptly. Your car's heater failure seems a bit early in the car's life.
As for what else to expect, that is hard to predict but there are many types of failures on the Model S, some of which are fairly common and some less so, same as with any car. You might find compilations of people's experience with older cars by doing some searches here,
Here is one example, but there have been many others: My Model S 85D and Tesla life at 100K miles
I think a lot depends upon how the car was stored and how it was driven. For example, I have had 4 or 5 door handle failures. Some people report having fewer or even none at the same age and mileage. My car has always been stored outside, and it has not traveled very many miles per year (but apparently more than yours, which seems to have had lower than average miles per year). Some people have theorized that the door handles are more likely to fail if cars are stored outside and subjected to extreme temperatures. As you appear to be in Canada, that might apply. On the other hand, heat is definitely a killer, especially for electronics and some other materials, so there might be some failures that are less common in cold climates.
One thing to be realistic about is that the Model S is the first car that Tesla ever designed from the ground up, so they certainly made some newbie mistakes and some choices of materials and components that did not pan out so well. By the time they made yours, they had learned a lot and made many (likely hundreds) of changes in materials and components, but it is still not a perfect car and stuff does wear out with time.
I bought nothing but used cars my entire life until I bought my Model S, so I might have a more relaxed attitude about having to get stuff fixed than some people do. But I will admit that I am seriously thinking about what to do when my 8-year battery and motor warranty runs out in a few months. Meanwhile I am trying to enjoy the car and not worrying too much about what might break.
Good luck, and I hope you enjoy your Model S!
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