P0AFA on Mercedes-Benz
14V Power Module System Voltage
P0AFA on Mercedes-Benz vehicles indicates 14v power module system voltage. Au7o has documented this code across 1 Mercedes-Benz model — most commonly on EQB. 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.
Common Causes of P0AFA
- •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
P0AFA on Mercedes-Benz by Model
Mercedes-Benz EQB(1 issue)
- High-Voltage Battery Cell Defect (Farasis Cells) Causing Internal Short and Fire Risk2022-2024
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%.
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View P0AFA across all makes →Frequently Asked Questions
What does P0AFA mean on 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 specifically, this code is documented across 1 model.
What causes P0AFA on Mercedes-Benz vehicles?▼
Common causes on Mercedes-Benz: 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. Specific causes vary by model and year — see the per-model sections below.
How much does it cost to fix P0AFA on a Mercedes-Benz?▼
Repair costs vary widely depending on the root cause and specific Mercedes-Benz model.
Which Mercedes-Benz models have P0AFA documented?▼
Au7o has documented P0AFA on 1 Mercedes-Benz model: EQB.