Mercedes-Benz Cooling system fault, operating en- ergy input reduced, service required
Cooling system fault, operating en- ergy input reduced, service required
Common search variants: Cooling system fault, operating energy input reduced, service required · Search ignores case and common separators.
Quick answer
For certain 2022–2025 Mercedes-Benz EQE and EQS vehicles in the US, this yellow instrument-cluster message is addressed by Mercedes-Benz bulletin LI83.30-P-079196. The bulletin identifies fault code B3A0077 and a battery-cooling refrigerant-circuit regulation valve (expansion valve Y140/1) that can stick open as the documented condition.
This page separates verified manufacturer/regulator evidence from supporting material. Unsupported causes, repairs or safety conclusions are not guessed.
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1. What does Cooling system fault, operating en- ergy input reduced, service required mean?
For certain 2022–2025 Mercedes-Benz EQE and EQS vehicles in the US, this yellow instrument-cluster message is addressed by Mercedes-Benz bulletin LI83.30-P-079196. The bulletin identifies fault code B3A0077 and a battery-cooling refrigerant-circuit regulation valve (expansion valve Y140/1) that can stick open as the documented condition.
2. Technical explanation
Mercedes-Benz bulletin LI83.30-P-079196 documents the message: “Cooling system fault, operating energy input reduced, service required.” In the bulletin’s described case, fault B3A0077 is stored: “The regulation valve in the refrigerant circuit for the battery cooling gets stuck open. The ordered position cannot be achieved.” The identified component is expansion valve Y140/1.
3. What system is affected?
Battery cooling refrigerant circuit; expansion valve Y140/1.
4. How serious is this code?
Not yet established by verified evidence. The message states that operating energy input is reduced and that service is required.
5. Symptoms you may notice
- Yellow instrument-cluster message: “Cooling system fault, operating energy input reduced, service required.”
- Reduced operating energy input, as stated in the message.
6. Possible causes
- For the condition described in Mercedes-Benz bulletin LI83.30-P-079196, expansion valve Y140/1 in the battery-cooling refrigerant circuit may be faulty and stuck open.
- Associated documented fault code: B3A0077 — “The regulation valve in the refrigerant circuit for the battery cooling gets stuck open. The ordered position cannot be achieved.”
7. Can I still drive the vehicle?
Not yet established by verified evidence.
8. Can I charge the vehicle?
Not yet established by verified evidence.
9. What you can safely do
- Arrange service with an authorized Mercedes-Benz service provider.
- Do not attempt refrigerant-system or high-voltage-system repairs yourself.
10. Step-by-step troubleshooting
- A qualified service provider can check whether fault B3A0077 is stored.
- A qualified service provider can check the part number of expansion valve Y140/1, as specified in Mercedes-Benz bulletin LI83.30-P-079196.
11. When to contact service
Mercedes-Benz bulletin LI83.30-P-079196 identifies this message as a service condition. Contact an authorized Mercedes-Benz service provider for diagnosis.
12. What the service center may check
- Confirm the yellow instrument-cluster message.
- Check for fault B3A0077.
- Check the part number of expansion valve Y140/1.
13. Possible repair or resolution
- For the bulletin-described condition, if Y140/1 has part number A 297 830 79 03 or older, Mercedes-Benz instructs replacement with A 297 830 89 03 or newer.
- The supplied evidence does not establish any repair outcome beyond the bulletin’s specified component replacement.
14. Affected vehicles
- Mercedes-Benz EQE · 2022–2025 · US
- Mercedes-Benz EQS · 2022–2025 · US
15. Related TSBs / service bulletins
- Mercedes-Benz LI83.30-P-079196, reported through NHTSA Manufacturer Communications 11017493 (published 2025-04-29), 11024516 (published 2025-10-27), and 11030093 (published 2026-03-12). It addresses the stated yellow message, B3A0077, and expansion valve Y140/1.
- Applicability supplied for this diagnostic: US-market 2022–2025 Mercedes-Benz EQE and EQS.
16. Recall information
- Not yet established by verified evidence.
17. Official manufacturer information
Official NHTSA manufacturer-communication records: 11017493, 11024516, and 11030093, all referencing Mercedes-Benz LI83.30-P-079196.
19. Frequently asked questions
What does this Mercedes-Benz message mean?
It is a yellow instrument-cluster message stating that a cooling-system fault is present, operating energy input is reduced, and service is required. For the condition in LI83.30-P-079196, Mercedes-Benz documents B3A0077 and a battery-cooling refrigerant-circuit regulation valve that is stuck open.
Which vehicles are covered by the supplied applicability data?
US-market 2022–2025 Mercedes-Benz EQE and EQS vehicles.
Can I drive or charge the vehicle?
Not yet established by verified evidence.
What repair does the Mercedes-Benz bulletin specify?
For the bulletin-described condition, the technician checks Y140/1. If its part number is A 297 830 79 03 or older, the bulletin specifies replacement with A 297 830 89 03 or newer.