iPhone NAND Repair Guide
NAND Faults & Communication Guide
Complete explanation about PCIe communication, SPI faults, Error 4013, Error 4014 and Error 9 diagnosis.
1. NAND Communication Overview
The CPU communicates with the NAND using high-speed PCIe communication lines. These lines handle booting, restoring and data transfer operations.
2. AP to NAND PCIe Communication
- PCIe AP to NAND REFCLK_N
- PCIe AP to NAND REFCLK_P
Faults may cause:
- Error 4014
- Restore failure
- Boot looping
- Recovery / DFU issues
3. NAND to AP Communication
- PCIe NAND to AP REFCLK_N
- PCIe NAND to AP REFCLK_P
Possible problems:
- Error 9
- Error 4013
- Data communication failure
- Restore stuck
4. SPI Communication (Link 0)
During early boot stages, the CPU uses SPI communication for NAND configuration.
- MISO (Master In Slave Out)
- MOSI (Master Out Slave In)
SPI line faults can cause:
- Device stuck in DFU
- Restore complete but no boot
- Recovery loop
5. PCIe Capacitor Faults
PCIe capacitors stabilize high-speed signals between CPU and NAND.
- Error 4013
- Error 4014
- Error 9
- Restore stuck at 19% or 20%
6. Important Diagnostic Checks
- Check PCIe capacitors
- Measure pull-up resistor values
- Inspect SPI communication lines
- Verify NAND voltage rails
- Check short circuits
- Inspect CPU ↔ NAND communication