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.
Call to confirm they can assess your vehicle and perform the stated work. Search results do not confirm qualification, eligibility or coverage.
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.