PCIe and expansion card error codes help diagnose failures related to PCI Express lanes, add‑in cards, slot power delivery, firmware initialization, and device communication. These codes may appear as POST codes, on‑screen messages, LED indicators, or diagnostic logs. Errors shown before the system logo usually indicate link training or slot power issues, while errors shown after the logo often point to driver, firmware, or resource conflicts.
Common PCIe Error Messages
- PCIe Link Training Failed — device cannot establish a stable PCIe connection
- PCIe Bus Error — communication fault between motherboard and expansion card
- PCIe Device Not Detected — card not seated, slot failure, or insufficient power
- PCIe Overcurrent Protection — slot power exceeded safe limits
- PCIe Enumeration Error — device cannot be assigned resources during boot
- Unsupported PCIe Device — incompatible card or outdated firmware
POST / Motherboard Diagnostic Codes (General)
- 92 — PCI Bus initialization
- 93 — PCI Bus hot plug initialization
- 94 — PCI Bus resource allocation
- 95 — PCI Bus setup complete
- 96 — PCI Bus driver loading
- B2 — Legacy Option ROM initialization (often GPU/PCIe related)
- B6 — NVRAM initialization (can indicate PCIe device conflict)
GPU‑Specific PCIe Error Codes
- VGA Error — GPU not detected or PCIe slot failure
- GPU POST Error — GPU firmware or PCIe link training issue
- PCIe x16 Link Downgraded — GPU running at x8/x4 due to lane problems
- GPU Power Fault — PCIe slot or auxiliary power cable issue
- Option ROM Load Failure — GPU BIOS could not initialize
Network Card (NIC) Error Codes
- Device Initialization Failure — NIC firmware or PCIe link issue
- PXE-E61 — NIC media test failure
- PXE-M0F — Exiting PXE ROM (NIC not responding)
- Link Down Error — PCIe NIC cannot establish network link
- MAC Address Read Error — corrupted NIC firmware
Storage Controller & NVMe Error Codes
- NVMe Device Not Found — PCIe lane or slot issue
- NVMe Critical Warning — temperature, power, or media failure
- PCIe Timeout — NVMe drive not responding to commands
- Link Width Reduced — NVMe running at x2/x1 due to lane failure
- Controller Initialization Error — firmware or PCIe negotiation failure
Sound Card Error Codes
- Audio Device Not Detected — PCIe slot or enumeration issue
- Driver Load Failure — firmware or resource conflict
- IRQ Conflict — legacy resource assignment problem
- DSP Initialization Error — sound card processor not responding
LED / Diagnostic Indicators (General)
- 1 blink — PCIe device not detected
- 2 blinks — PCIe lane training failure
- 3 blinks — slot power delivery issue
- 4 blinks — device firmware initialization error
- 5 blinks — PCIe communication timeout
Troubleshooting Steps
- Reseat the expansion card firmly in the PCIe slot
- Test the card in another PCIe slot
- Inspect for bent pins or debris in the slot
- Check auxiliary power cables for GPUs or high‑power cards
- Update motherboard BIOS and device firmware
- Verify correct PCIe lane configuration in BIOS
- Remove other cards to rule out resource conflicts
- Replace failing cards or motherboard slots