P0AFA on Mercedes-Benz: How to Diagnose & Fix
14V Power Module System Voltage
1 Mercedes-Benz model · 1 documented issue · 1 critical
P0AFA on Mercedes-Benz by model: symptoms, diagnosis and fix
Certain EQB high-voltage battery packs built with early-production lithium-ion cells from Farasis Energy (Ganzhou, China) contain cells that are insufficiently robust against stress factors at high state of charge. A deviation in the supplier's production process allows an internal short circuit to develop over time, which can escalate to a thermal event and vehicle fire while parked or driving. Mercedes-Benz has confirmed fire incidents in the US. The campaign has been revised three times: NHTSA 25V050 (Feb 2025, software-only), 25V894 (Dec 2025, BMS software), and finally 26V073 (Feb 2026), which supersedes both and replaces the pack outright. Roughly 11,895 US vehicles built Dec 2021 - May 2024 are covered. Interim guidance is to park outdoors away from structures and charge to no more than 80%.
Common Symptoms
- Recall notice instructing owner to park outdoors
- Charging limited to 80% by dealer or software update
- Battery warning or reduced charge capacity
- Burning smell or smoke in extreme cases
- Reduced usable range after BMS software update
How to Fix
Have the recall performed at a Mercedes-Benz dealer - under 26V073 the entire high-voltage battery is replaced free of charge, even if the vehicle was already 'repaired' under the earlier software-only campaigns 25V050 or 25V894. Until the pack is replaced, cap charging at 80% (set the charge limit in MBUX), avoid leaving the car at high SOC for long periods, and park outside and away from buildings. Check your VIN on nhtsa.gov/recalls, since the phased parts supply means notification dates vary.
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Sources for this issue (4)
- NHTSA Recall 26V073 - Mercedes-Benz EQB High Voltage Battery Fire Risk (recall acknowledgement)article
- NHTSA Recall Report 25V050 - Mercedes-Benz EQB high voltage batteryarticle
- Mercedes Recalls The EQB EV For The Third Time To Try And Stop Battery Firesarticle
- Mercedes-Benz EQB 300 Recalls - Cars.comarticle
P0AFA code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0AFA mean on a Mercedes-Benz?
P0AFA stands for "14V Power Module System Voltage." P0AFA is a hybrid/electric vehicle code indicating the computer detected low voltage in the 14-volt power module system — the converter that supplies the conventional 12V/14V electrical system in a hybrid or EV (the equivalent of a traditional alternator). The 14V power module (often a DC-DC converter) steps down the high-voltage battery to power lights, accessories, and the auxiliary 12V battery. When the monitored output voltage falls below the expected threshold, this code is set. It generally indicates the low-voltage electrical system isn't being properly charged, which can lead to a dead 12V battery and a no-start condition. On Mercedes-Benz it is documented across 1 model: EQB.
What are the most common causes of P0AFA?
The most common causes of P0AFA are: Failing DC-DC converter / 14V power module, Weak or failing auxiliary 12V battery, Corroded or loose 12V battery terminals and ground connections, Damaged wiring or connectors in the low-voltage charging circuit, Excessive electrical load draining the system, Fault in the high-voltage battery supply to the converter, Internal control module or software fault. The specific cause varies by vehicle.
How much does it cost to fix P0AFA on a Mercedes-Benz?
Repair costs vary widely with the root cause and Mercedes-Benz model; each issue on this page carries its own estimate where one is published.
Looking for P0AFA on a different make?
View P0AFA across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.