Chronic critical errors

[CME]

I bought my Model S P85D in December 2014, and for the first two years, it worked fine without any major issues. However, starting from March 2017, it started to have random yet serious problems. The car would randomly generate critical errors, displaying multiple error messages while losing most of its driving power (a.k.a., entering “limp mode”). When this happens, the driver has to do emergency pullovers onto road shoulders and restart the main computer to make the car drivable again.

Needless to say, this is both annoying and dangerous, so I contacted Tesla right away. This turned out to be a serious problem that Tesla has been unable to fix. In the next five and a half years, for this problem alone, my Tesla has been in the service centers for 11 times, a total of 397 days.

As of January 2023, the following components had been replaced: onboard charger, charger door, MCU, various harnesses, HV battery, inverter, THC, Monocam, etc. However, the problem just keeps coming back.

The problem seems to be related to battery charging and re-gen; the following factors seem to contribute to the likelihood of it happening:

• Driving right after a full charge
• The first 20 minutes drive after a recharge is the most vulnerable
• Normal re-gen (vs. low re-gen)
• The number of times power transitioned from Power to Regen mode
• Sports/insane mode (vs. chill mode)
• Complicate traffic or road conditions make it more prone to having this problem.

It has some characteristics of a memory corruption problem, but MCU was replaced and the problem persisted, it seems to contradict that proposition.

Any idea or suggestion would be very much appreciated.

 

[ewoodrick]

I bought my Model S P85D in December 2014, and for the first two years, it worked fine without any major issues. However, starting from March 2017, it started to have random yet serious problems. The car would randomly generate critical errors, displaying multiple error messages while losing most of its driving power (a.k.a., entering “limp mode”). When this happens, the driver has to do emergency pullovers onto road shoulders and restart the main computer to make the car drivable again.

Needless to say, this is both annoying and dangerous, so I contacted Tesla right away. This turned out to be a serious problem that Tesla has been unable to fix. In the next five and a half years, for this problem alone, my Tesla has been in the service centers for 11 times, a total of 397 days.

As of January 2023, the following components had been replaced: onboard charger, charger door, MCU, various harnesses, HV battery, inverter, THC, Monocam, etc. However, the problem just keeps coming back.

The problem seems to be related to battery charging and re-gen; the following factors seem to contribute to the likelihood of it happening:

• Driving right after a full charge
• The first 20 minutes drive after a recharge is the most vulnerable
• Normal re-gen (vs. low re-gen)
• The number of times power transitioned from Power to Regen mode
• Sports/insane mode (vs. chill mode)
• Complicate traffic or road conditions make it more prone to having this problem.

It has some characteristics of a memory corruption problem, but MCU was replaced and the problem persisted, it seems to contradict that proposition.

Any idea or suggestion would be very much appreciated.

How's the 12V battery? 2014-2017 is just about the time that it takes for the battery to deteriorate. Hopefully you have replaced it, hopefully twice.

 

[MP3Mike]

he car would randomly generate critical errors, displaying multiple error messages while losing most of its driving power (a.k.a., entering “limp mode”).

It would help if you shared the error codes...

It has some characteristics of a memory corruption problem, but MCU was replaced and the problem persisted, it seems to contradict that proposition.

The MCU isn't really involved in the driving of the vehicle. (Why you can reboot it while you are driving without issues.)

My first guesses would be a ground point issue, but that probably wouldn't have any relation to problems occurring after regen/charging
My second guess would be the drive-unit/inverter.

 

[CME]

How's the 12V battery? 2014-2017 is just about the time that it takes for the battery to deteriorate. Hopefully you have replaced it, hopefully twice.

Yes, the 12V battery was replaced in Nov 2019, along with the main HV battery, it didn't fix the problem.

 

[CME]

It would help if you shared the error codes...


The MCU isn't really involved in the driving of the vehicle. (Why you can reboot it while you are driving without issues.)

My first guesses would be a ground point issue, but that probably wouldn't have any relation to problems occurring after regen/charging
My second guess would be the drive-unit/inverter.

In August 2018, they replaced the rear drive harness and inverter, it didn't help; 3 months ago, when this problem reoccurred after last year's "fixes" (replacing several other harnesses), they told me they need to replace the rear drive unit, and gave me an estimate of $8,000. I didn't accept the proposal.

The funny thing is, most of those previous fixes were based on different error codes they "read", they genuinely believed those were the root causes and were very confident "it's fixed this time", the result was one disappointment after another.

I don't know how the error codes were triggered, stored, and propagated, but my guess is, they were "ghost" errors that were not created by lower level hardware modules, but "fake" ones created by the software itself.

 

[CME]

Does anyone know where I can find information on Model S's software system diagram? i.e. how CPU memory space is utilized and how it's recycled?

 

[JanEllingsen]

Have a 2014 P85Plus with the same multiple error codes and suddenly drop of power steering while driving. Have had it before as well and that time the service shop found a common grounding point to be the problem. So now after a year or so it has come back. Any idea what ground point that they are talking about? Think the only sanded down the connection point and not adding any alu paste. Do not want to pay anything just for this so any chance someone know what common grounding point they are talking about? Guessing that it is in the frunk some place.

EPAS_w002 Redused power steering
ESP_w003 Anti spinn deactivated
ESP-w001 ABS deactivated
and also regenerated charging deactivated

 

[JanEllingsen]

Found the problem. Common ground point left side corroded and broken off. Made a quick fix to have it working back from the cabin.