Oppo AX5 (also sold as Oppo R15 Neo in some markets) with model CPH1851/CPH1851EX is a mid‑range Android smartphone based on the Qualcomm Snapdragon 450 platform with ColorOS 5.1 on Android 8.1 Oreo.
The firmware packages listed below are official ColorOS update and service builds for the global “EX_11” line (variants A.01 through A.15), used for unbricking, fixing bootloops, and applying staged OTA‑equivalent updates.
These are Qualcomm OFP/zip/rar service packages that can be installed either via stock recovery (for update zips) or via Oppo/Qualcomm flashing tools when unbricked service access is required.
Oppo AX5 / R15 Neo CPH1851EX Firmware Details
| Field | Information |
|---|---|
| Device Name | Oppo AX5 / Oppo R15 Neo (CPH1851 / CPH1851EX) |
| Model Identifier | CPH1851 / CPH1851EX (global/EX variant family) |
| Codename | Project config 18335 for CPH1851EX firmware line |
| Chipset / Platform | Qualcomm Snapdragon 450 (SDM450), octa‑core Cortex‑A53, Adreno 506 GPU |
| Launch Android Version(s) | Android 8.1 Oreo with ColorOS 5.1 out of the box |
| Current Firmware Line | CPH1851EX_11_A.xx ColorOS 5.1 (Android 8.1) stable line; builds from A.01 up to at least A.24 documented. |
| Firmware Type | Official Oppo EX_11 service/update packages (OFP/service zips/archives for recovery or Oppo flashing tools) |
| Flashing Tool | Oppo Recovery / Local Update for update zips, and Qualcomm‑based Oppo flash tool (DownloadTool/MSM variant) or QPST/QFIL‑based service tools for OFP/service builds. |
| Bootloader Requirement | Designed for locked bootloader devices; official packages install via recovery or authorized service flashing with appropriate Oppo/Qualcomm authentication where required. |
| Region / Branch Notes | “EX” denotes global/export firmware; cross‑flashing to China‑only or carrier‑specific variants is not advised due to modem/region differences. |
| Typical File Size Range | Approx. 3.4–4.6 GB per package, depending on build (A.01–A.15 in this list). |
| Partition / Package Contents | Qualcomm‑style full images (boot, system, vendor, modem, dsp, etc.) packaged for Oppo’s OFP/zip distribution and service flashing. |
| Verification Note | Flashing method family (Oppo recovery / Oppo Qualcomm tool) verified via multiple independent references for the CPH1851EX_11_A.15 and related builds. |
⚠️ Flashing Risks & Disclaimer
Flashing Oppo AX5 / R15 Neo firmware carries risks typical for Qualcomm/ColorOS devices, including modem or Widevine issues if wrong region firmware is used, and potential hard‑brick if service packages are flashed incorrectly with unauthorized tools.
Only use CPH1851EX_11 builds on confirmed CPH1851/CPH1851EX devices, and avoid mixing EX firmware with carrier‑locked or region‑specific models.
All packages remain the property of Oppo and are provided strictly for restoring or updating legitimately owned phones; mirrored files are preservation copies, not new “official server” endpoints.
Download Firmware for Oppo AX5 / R15 Neo (CPH1851EX)
Many of these builds are now hosted on third‑party mirrors (Google Drive, MediaFire, community firmware sites) because original public Oppo postings are harder to access for older devices. Each file below is an original Oppo EX_11 package mirrored for preservation, as the manufacturer no longer surfaces all of these builds via public download pages.
| Region / Variant | Filename | Build / Version | Android / Firmware Version | File Type | Build Date | File Size | Download Link |
|---|---|---|---|---|---|---|---|
| Global EX – early AX5 build | Oppo_AX5_CPH1851_EX_11_A.01_180816.zip | EX_11_A.01_180816 | ColorOS 5.1 / Android 8.1 (initial EX release) | ZIP (Oppo update package; suitable for recovery/local update) | 2018‑08‑16 (from build tag 180816) | 4.37 GB | Download A.01 180816 (Google Drive mirror) |
| Global EX – later AX5 build | Oppo_AX5_CPH1851_EX_11_A.07_190128.zip | EX_11_A.07_190128 | ColorOS 5.1 / Android 8.1 (stability/security update over early builds) | ZIP (Oppo update package; recovery/local update) | 2019‑01‑28 (from build tag 190128) | 4.52 GB | Download A.07 190128 (Google Drive mirror) |
| Global EX – intermediate update | CPH1851EX_11_A.04_180924_77ab15fa.rar | EX_11_A.04_180924 | ColorOS 5.1 / Android 8.1 (incremental EX_11 line update) | RAR archive containing Oppo firmware package (service/update) | 2018‑09‑24 (from build tag 180924) | 3.93 GB | Download A.04 180924 (Google Drive mirror) |
| Global EX – intermediate update | CPH1851EX_11_A.05_181109_77ab15fa.rar | EX_11_A.05_181109 | ColorOS 5.1 / Android 8.1 (bugfix/optimization update) | RAR archive containing Oppo firmware package (service/update) | 2018‑11‑09 (from build tag 181109) | 3.95 GB | Download A.05 181109 (Google Drive mirror) |
| Global EX – mid‑cycle update | CPH1851EX_11_A.07_190128_e3b3014e.rar | EX_11_A.07_190128 | ColorOS 5.1 / Android 8.1 (same base as AX5 A.07, different packaging) | RAR archive (service/offline package) | 2019‑01‑28 (from build tag 190128) | 4.01 GB | Download A.07 190128 (RAR, Google Drive mirror) |
| Global EX – later A‑series update | CPH1851EX_11_A.11_190716_f63a448a.rar | EX_11_A.11_190716 | ColorOS 5.1 / Android 8.1 (security and stability update) | RAR archive (Oppo service/update package) | 2019‑07‑16 (from build tag 190716) | 3.8 GB | Download A.11 190716 (Google Drive mirror) |
| Global EX – late 2019 update | CPH1851EX_11_A.12_190925_fd1e2a2d.zip | EX_11_A.12_190925 | ColorOS 5.1 / Android 8.1 (late‑2019 maintenance/security update) | ZIP archive (Oppo service/update package) | 2019‑09‑25 (from build tag 190925) | 3.9 GB | Download A.12 190925 (MediaFire mirror) |
| Global EX – A.15 late‑2019 build | CPH1851EX_11_A.15_191230_5c53d686.7z | EX_11_A.15_191230 | ColorOS 5.1 / Android 8.1 (December 2019 update; often used as stable target for repairs) | 7z archive containing official Oppo OFP/service firmware | 2019‑12‑30 (from build tag 191230) | 3.47 GB (archive size; extracted OFP is larger) | Download A.15 191230 (MediaFire mirror) |
For all MediaFire‑ or community‑hosted entries above, each file is an original Oppo EX_11 ROM mirrored for preservation, as the manufacturer no longer provides easy public access to every historical AX5/R15 Neo build.
Flashing Requirements
- Windows PC is strongly recommended, as Oppo’s Qualcomm tools and drivers are Windows‑centric.
- Qualcomm USB drivers (QDLoader) plus either Oppo DownloadTool/MSM‑based flasher for OFP/service packages, or a properly signed stock recovery for local OTA zips.
- Locked bootloader is expected; service tools may require authorized login for full flashing on newer security revisions.
- Battery charged to at least 40–50% to avoid shutdown mid‑flash.
- Backup user data where possible, since many full‑package flashes and some recovery updates can wipe data and settings.
- Confirm the device model is CPH1851/CPH1851EX (AX5/R15 Neo) via Settings or fastboot/label before flashing any EX_11 build.
How to Flash the Firmware
- Choose the appropriate CPH1851EX_11 build (for example, A.15_191230 for a late, stable Android 8.1 ColorOS release) and download the archive from the table above, extracting it if it is in 7z/rar format to reveal the OFP/zip package.
- For recovery‑flashable update zips (AX5_CPH1851_EX_11_A.xx_xxxxxx.zip), copy the zip to the phone’s internal storage or SD card; for OFP/service builds, install Oppo/Qualcomm drivers and open the appropriate Oppo flashing tool on the PC.
- If using stock recovery, power off the AX5, then boot to recovery (typically Power + Volume Down/Up depending on region), choose “Install from storage” or “Local update”, and select the downloaded EX_11 zip.
- If using service tools, place the device into EDL or the tool’s required download mode, load the CPH1851EX_11 package in the Oppo tool, double‑check that the target device is CPH1851EX, and start the flash.
- After installation completes, reboot the phone; the first boot may take several minutes as ColorOS 5.1 and Android 8.1 rebuild caches and optimize installed applications.
For a more general Qualcomm/fastboot‑style stock flashing overview (helpful as background, though AX5 uses Oppo‑specific tooling), see: How to flash stock firmware using fastboot.
Frequently Asked Questions (FAQs)
Which CPH1851EX build is recommended for recovery?
In many repair scenarios, a later stable build such as CPH1851EX_11_A.15_191230 is preferred because it includes more recent security and bug fixes while staying on the supported ColorOS 5.1 / Android 8.1 line.
Can these EX_11 ROMs be used on non‑EX or carrier‑locked AX5 variants?
No, EX firmware is intended for CPH1851EX/global devices; flashing on mismatched region or carrier variants may cause modem or feature issues and should be avoided.
Is an unlocked bootloader required on Oppo AX5 / R15 Neo?
No, official Oppo EX_11 packages and service tools are designed for use with locked bootloaders, though some functions may require authorized service credentials.
Can these builds fix a device stuck on the Oppo logo or in a bootloop?
A correct CPH1851EX_11 full flash can often resolve software‑level bootloops, failed update states, or system UI crashes, provided the hardware is healthy and matches the EX model.
Are the Google Drive and MediaFire URLs official Oppo servers?
No, these are third‑party mirrors and community archives hosting original Oppo AX5/R15 Neo EX_11 packages for preservation after Oppo’s public hosting made older builds harder to obtain.
Can these builds be used to downgrade from a newer CPH1851EX_11 version?
Downgrade between EX_11 builds (for example, from A.15 back to A.11) is sometimes possible but not officially recommended; it should only be attempted with full backups and awareness of potential rollback limitations.
