Yellow Electrical System Error - Service Required

[CrazyINP]

At this point I'm going back to the Los Gatos place and will insist on driving the car to the charger with the tech onboard so I can ensure the correct repro case.

you making me paranoid now! I have never used fast charging on my car. Really haven't had the need. Now I will go try it out.

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[DerekS]

you making me paranoid now! I have never used fast charging on my car. Really haven't had the need. Now I will go try it out.

Well, to do it right:
- SoC low (15% or less)
- Add the charger to the GPS so it will preheat, will be around 100F when you arrive
- Plug into a good 350kW charger that actually works which is hard to come by.

The one at Coleman Landing over by SJC was a good one that delivered full rate for me.

 

[tigerbalm]

road elephant

Stealing this phrase!

 

[tigerbalm]

Sigh. I hate that Porsche doesn’t have techs that understand EVs.

They ignored my instructions, which were very explicit, filled the car to 100% on a 150kW charger (which of course didn’t reproduce the fault.)

At this point I am pissed, have now failed to fix this issue at two separate service centers, and I’m fed up.

If anyone knows a service center that ACTUALLY UNDERSTANDS EVS or at least FOLLOWS THE DIRECTIONS I TYPE UP please give me a recommendation.

I had a similar problem with reproducing a charging error on my Turbo S. It would fail every time but only if it started at a low state-of-charge and was on a 350 kW charger.

They tried for days to reproduce it on both AC and the 150 kW charger they had available, but it was always fine.

I eventually managed to organise a technician to drive with me to a 350 kW charger which was 50 km away and plug in their PIWIS computer while it charged and failed.

For the first time in weeks, the damn thing refused to fail when plugged into the computer. I could not understand it! The one time I needed it to fail, it refused.

I dropped the technician back at Porsche Centre and went to work. That evening, out of frustration I drove back to that station and tried again. It immediately failed – refused to take in any energy. I tried on a few more charging stations – and failure each time.

Porsche Centre now could see the failure easily and the fix was straightforward.

Nothing worse than a complicated failure reproduction process that involves off-site charging. I was so thankful the thing eventually completely broke.

Nowadays there is a 12-pedestal IONITY station right outside the (only) Porsche Centre in Republic of Ireland. It would have been a much easier thing to try and reproduce today for me!

Thread on the issue at the time:

https://www.taycanforum.com/forum/threads/dc-charging-issue-failures.18261/

 

[DerekS]

Picked up the car today. Issue not fixed, though they did fix the stupid seat recall so I guess I have that going for me, which is nice.

SoC over 75%, so the car is not in a position to reproduce for another week. Got a bunch of nonsensical stuff about codes and firmware on the 11kW AC charger, which has exactly nothing to do with my fast DC fault under maximum load.

Current game plan is run it down, again, and either:

- Pick up a Porsche tech from Los Gatos and take them with me to the charger
- Or, get the car into the fault state and get to the dealer to pull codes as quickly as possible to try and diagnose.

The next time I reproduce it also need to pay attention to the fans. If memory serves, those fans ought to be absolutely screaming when I'm doing 250-270kW. Maybe the problem is as simple as that; fans out, getting too hot under load.

Chat GPT suggested the following:

TAS Case Narrative (Use This Text)
Concern:
Customer reports repeated Electrical System Fault message during high-power DC charging. Charging does not stop; vehicle continues charging at reduced power. Warning clears after battery cools (approx. 45–90 minutes). Concern is reproducible only under maximum HV charging load.

Reproduction Conditions:
Occurs when:

• SOC < 15%
• HV battery preconditioned for fast DC charging
• Connected to operational >250 kW charger (e.g., EA 350 kW)
• Battery temperature rises into approx. 46–53°C (115–128°F) range

Observed Behavior:
Battery thermal management enters protection mode during high current fast charge. System derates charge power and sets yellow “Electrical System Error” warning without stopping charge session. No faults stored if vehicle is allowed to sleep before analysis.

Requested Diagnostic Actions:

1. Retrieve DCS Charge Session Log within 60 minutes of event, prior to vehicle sleep:
   PIWIS → High Voltage Battery → Fault Memory → DCS Charge Session Data → Export
2. Perform Actuator Test of Radiator Fans under HV Battery Thermal Management (J1024):
   PIWIS → J1024 → Actuators → Radiator Fan Left (V7) → Activate → Stage 4
   PIWIS → J1024 → Actuators → Radiator Fan Right (V177) → Activate → Stage 4
3. Compare Commanded RPM vs Actual RPM at Stage 4.
   If actual < commanded, likely underperformance of cooling circuit at high thermal load.

Suspected Components Based on Symptom Pattern:

• Radiator Fan Assembly V7 and/or V177 (reduced output at high duty cycle)
• Cooling plate flow restriction / coolant distribution imbalance
• Less likely: Temp sensor deviation in battery module group (evaluated via DCS log)

Notes:
This concern does not require onsite high-power charger to reproduce, as fan stage ramp is confirmed via actuator test. DCS session log is required to identify module-level thermal gradient behavior.

 

[Scandinavian]

Derek, have you ever tried to switch to Sport Plus mode while sitting in the car as it’s charging?

If it is not too cool outside, that has done it for me . The car charges at 260 kW and the fans run like mad for a while. Try it to see if the fans spin up

 

[Tooney]

Chat GPT suggested the following:

TAS Case Narrative (Use This Text)
Concern:
Customer reports repeated Electrical System Fault message during high-power DC charging. Charging does not stop; vehicle continues charging at reduced power. Warning clears after battery cools (approx. 45–90 minutes). Concern is reproducible only under maximum HV charging load.

Reproduction Conditions:
Occurs when:

• SOC < 15%
• HV battery preconditioned for fast DC charging
• Connected to operational >250 kW charger (e.g., EA 350 kW)
• Battery temperature rises into approx. 46–53°C (115–128°F) range

Observed Behavior:
Battery thermal management enters protection mode during high current fast charge. System derates charge power and sets yellow “Electrical System Error” warning without stopping charge session. No faults stored if vehicle is allowed to sleep before analysis.

Requested Diagnostic Actions:

1. Retrieve DCS Charge Session Log within 60 minutes of event, prior to vehicle sleep:
   PIWIS → High Voltage Battery → Fault Memory → DCS Charge Session Data → Export
2. Perform Actuator Test of Radiator Fans under HV Battery Thermal Management (J1024):
   PIWIS → J1024 → Actuators → Radiator Fan Left (V7) → Activate → Stage 4
   PIWIS → J1024 → Actuators → Radiator Fan Right (V177) → Activate → Stage 4
3. Compare Commanded RPM vs Actual RPM at Stage 4.
   If actual < commanded, likely underperformance of cooling circuit at high thermal load.

Suspected Components Based on Symptom Pattern:

• Radiator Fan Assembly V7 and/or V177 (reduced output at high duty cycle)
• Cooling plate flow restriction / coolant distribution imbalance
• Less likely: Temp sensor deviation in battery module group (evaluated via DCS log)

Notes:
This concern does not require onsite high-power charger to reproduce, as fan stage ramp is confirmed via actuator test. DCS session log is required to identify module-level thermal gradient behavior.

Where is Chat GPT getting those troubleshooting steps? What is the source of the detailed information?

 

[DerekS]

Where is Chat GPT getting those troubleshooting steps? What is the source of the detailed information?

TSBs online? Could be straight lies. Who knows.

 

[DerekS]

Can the folks interested in this thread confirm something?

1. Do the fans spin up super loud during fast DC > 250kW?
2. Do the fans spin up when you put the car in Sport Plus?

I have a working theory that my issue is as simple as seized fans. I'm still working on draining the car so I can reproduce my issue again. In the meantime I've been using a lot of Sport Plus and do NOT notice fan spinup.

 

[DerekS]

Ok I am now pretty certain seized fan is my issue.

I got the battery up to 114F today (by Sport Plus + Charger in route planner + Max AC + ~20-30 mins). The right fan turned and the left did not.

I learned from the tech today that the left fan is for battery cooling and the right is for AC condenser. TIL.
Car is back at the Los Gatos service center.

To confirm I'm on the right track, can anyone else get their battery up to that temp and see if their left fan is blowing?

 

[GHamilton]

Derek, have you ever tried to switch to Sport Plus mode while sitting in the car as it’s charging?

If it is not too cool outside, that has done it for me . The car charges at 260 kW and the fans run like mad for a while. Try it to see if the fans spin up

That's very interesting if the drive mode affects charging...don't understand that one!

 

[WalterG]

Ok I am now pretty certain seized fan is my issue.

I got the battery up to 114F today (by Sport Plus + Charger in route planner + Max AC + ~20-30 mins). The right fan turned and the left did not.

I learned from the tech today that the left fan is for battery cooling and the right is for AC condenser. TIL.
Car is back at the Los Gatos service center.

To confirm I'm on the right track, can anyone else get their battery up to that temp and see if their left fan is blowing?

I don’t think it’s as simple as left for battery and right for a/c the was the dealer described it. Whenever I’ve fast charged, the right fan runs hard and there is so much heat that my right front tire pressure goes up a few degrees vs the other 3 tires. I don’t remember the left being on normally for dc charging (or at least it didn’t make as much noise or push as much heat as the right). I asked ChatGPT (fwtw). Here’s the reply and this actually aligns with my experience. I can’t test it this weekend but could next week if it’s not figured out by then.

Chatgpt reply:
Left front (driver side): the fan pulls air through the low/mid-temperature radiator that cools the drive units and power electronics and also supports battery thermal management via the chiller.
Right front (passenger side): the fan serves the A/C condenser / heat-pump circuit (the “high-temp” side). It’s commanded on for cabin A/C and when the system uses the A/C loop to pull extra heat out of the battery during fast charging or hot conditions.

Notes: Taycan has two separate front corner fans/radiators (left and right assemblies are listed in Porsche parts catalogs), and owners commonly describe the left as “battery/drive cooling” and the right as “A/C/heat-pump.” Both can run together (e.g., during DC fast charging).

During DC fast charging the car uses the A/C loop + chiller to pull heat from the battery; that heat is rejected at the A/C condenser located at the front-right, so the right fan usually runs.

Left-front fan: only if needed. The left side serves the mid-temp radiator for motors/inverters; it may kick on to help overall thermal balance (e.g., hot ambient, back-to-back fast charges, or after hard driving), but it’s not guaranteed during DCFC. Owners commonly observe right-only operation in normal conditions

 

[DerekS]

I don’t think it’s as simple as left for battery and right for a/c the was the dealer described it. Whenever I’ve fast charged, the right fan runs hard and there is so much heat that my right front tire pressure goes up a few degrees vs the other 3 tires. I don’t remember the left being on normally for dc charging (or at least it didn’t make as much noise or push as much heat as the right). I asked ChatGPT (fwtw). Here’s the reply and this actually aligns with my experience. I can’t test it this weekend but could next week if it’s not figured out by then.

Chatgpt reply:
Left front (driver side): the fan pulls air through the low/mid-temperature radiator that cools the drive units and power electronics and also supports battery thermal management via the chiller.
Right front (passenger side): the fan serves the A/C condenser / heat-pump circuit (the “high-temp” side). It’s commanded on for cabin A/C and when the system uses the A/C loop to pull extra heat out of the battery during fast charging or hot conditions.

Notes: Taycan has two separate front corner fans/radiators (left and right assemblies are listed in Porsche parts catalogs), and owners commonly describe the left as “battery/drive cooling” and the right as “A/C/heat-pump.” Both can run together (e.g., during DC fast charging).

During DC fast charging the car uses the A/C loop + chiller to pull heat from the battery; that heat is rejected at the A/C condenser located at the front-right, so the right fan usually runs.

Left-front fan: only if needed. The left side serves the mid-temp radiator for motors/inverters; it may kick on to help overall thermal balance (e.g., hot ambient, back-to-back fast charges, or after hard driving), but it’s not guaranteed during DCFC. Owners commonly observe right-only operation in normal conditions

Well shit. That means I’m going to get a passed fan test and my problem will remain undiagnosed.

 

[WalterG]

Well shit. That means I’m going to get a passed fan test and my problem will remain undiagnosed.

128F for the battery temp seems high to me. I don’t remember going much above 115. And during dc charging the temp seems pretty stable or even drops a little because the car is dumping so much heat. You might be on the right track suspecting a cooling problem even though the fan is working.

 

[WattTurbo]

Agreed it’s the passenger fan that cools the battery when I charge it. Mine has not gone over 112F but I always have the battery friendly mode on.

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