Map Validity Check Tool (In-App)
Requirements: Custom Code v7.3 or later, and MG Flasher app version 483 or later.
What it does
The Map Validity Check tool reads every validity parameter from the DME in real time and presents a color-coded overview of every switchable map slot, fuel type, and individual map. It helps you quickly identify:
Missing or null map data — slots that were not properly configured by the tuner.
Disabled features — codewords or blending factors that are intentionally turned off.
Flex fuel blending issues — whether FF1/FF2 maps are populated and their blending factors are valid.
Its a diagnostic tool (mainly for tuners) which used the DME to identify all maps have been correctly enabled. During DME bootup, the Custom Code in the DME already scans every cell of every map for validity (see Safety & Validity Checks). This in-app tool lets you see exactly what the DME sees — before you start the engine.
How to access
Connect to your car via ENET using the latest version of the MG Flasher app.
Open the My Car page.
Tap Custom Code Diagnostics.
Tap Map Validity Check.
The app will automatically read all validity parameters from the DME when the page opens.
Understanding the overview grid
The first screen shows a grid with one row per slot and three fuel‑type columns. Each column means:
Column | Meaning |
|---|---|
Slot | The slot number (0–4). Tap to see per-map details for the entire slot. |
PF (Pump Fuel) | Validity status when running on pump fuel. |
FF1 (Flex Fuel 1) | Validity status for the first flex fuel blend. |
FF2 (Flex Fuel 2) | Validity status for the second flex fuel blend (if configured). |
Color coding
Green — Valid: All maps in this slot/fuel combination pass the validity check: enabled or valid data.
Red — Invalid: One or more maps contain invalid/corrupt or null data. May also be used to indicate critical maps/items that are disabled.
Grey — Disabled: The relevant codeword(s) are not enabled, so this slot/fuel/map is not active.
Special: Slot 0
Slot 0 / Pump Fuel always shows N/A with a green background. This is the OEM data location and is always considered valid; its contents are not part of the switchable map validation.
Drilling into details
Tap any cell (PF/FF1/FF2) or slot header to open the details page. The details page breaks down the validity status into four collapsible sections.
1. Codewords
Shows whether the relevant codewords are Enabled or Disabled:
Map Switch — controls whether switchable maps are active at all.
Map Switch Slot N — controls whether this specific slot is active.
Flex Fuel Blending — controls whether flex fuel blending is active.
Flex Fuel Blending Slot N — controls whether this specific slot participates in blending.
Per-map codewords — some maps have individual map‑level codewords that can independently enable or disable those maps.
If a codeword is disabled, the corresponding maps show as grey/disabled in the grid. This is expected behavior, not an error.
2. Blending Factors (FF1/FF2 only)
Visible only when viewing a flex fuel cell. Shows whether the blending factor parameters for this slot contain valid data.
"Requires valid FF2 maps" entries indicate whether FF2‑specific blending factors are expected for this slot.
This section is hidden when viewing a Pump Fuel cell.
3. Slot Validity
The aggregate slot‑level ValidData parameter — a single value the DME checks during bootup:
CustomCode_SwitchableMaps_slot{N}_{Fuel}_ValidData
4. Map Validity (per-map breakdown)
Each individual map is listed with its validity state per fuel type:
CustomCode_DataValid___{MapName}___{Fuel}_slot{N}
Maps are sorted by severity in this order:
Invalid (red) first
Valid (green)
Disabled (grey)
A quick-count summary at the top shows: X Invalid · Y Valid · Z Disabled.
No blending factors section; it is not checked for Pump Fuel
Platform-specific maps
Some maps only apply to specific engine families. The app automatically filters them based on the connected vehicle. A grey, italic note under the map name indicates platform availability. Here’s an example list of maps that have platform restrictions:
Map | Engine |
|---|---|
| S58 only |
| B-Series only |
| Gen 2 B/S-series only |
| Gen 1 B-series only |
| Gen 1 hybrid (R1C9I562B) only |
Slot 0 details
When you tap the Slot 0 header, the details page shows a summary message: "Slot 0 is always enabled and has no validation checks." No per‑map rows are displayed for Slot 0 / Pump Fuel.
Not checked for validity, you can always switch to it.
Sharing results
After a successful read, tap the Share button at the bottom of the overview grid to export a self-contained HTML report.
The report includes:
VIN and timestamp.
The full overview grid with color coding.
Per-cell detail breakdowns (all four sections).
Styled to match the in-app experience — viewable in any browser.
Share the HTML file via email, messaging apps, or upload to Slack for your tuner to review exactly the same validity view you see in the app.
Example HTML
Here’s an example export you can download and browse:
Troubleshooting
"Core parameters not available"
The connected Custom Code version does not support map validity parameters. Ensure you are running Custom Code v7.3 or later. Reflash with a compatible Custom Code version if needed.
"No results generated"
The read completed but returned no data. This can happen if:
The A2L definition for the connected SWFL does not include validity parameters.
There was a connection issue during the read.
Try disconnecting and reconnecting, then re-enter the Map Validity page.
A cell is red — what do I do?
A red cell means one or more maps in that slot/fuel contain null or corrupt data. All cells for slots and fuel types you actively use should normally be green. Tap the cell to see exactly which map(s) failed.
Common causes:
The tuner did not populate that slot. Contact your tuner and ask them to fill the slot or disable the codeword for that slot.
A partial flash occurred. Reflash the tune file to ensure all map data was written correctly.
The slot is using default/unpopulated OEM space. If you don't intend to use that slot, ensure the corresponding codeword is disabled in your tune.
A cell is grey/disabled
Grey cells are expected when a feature is not enabled. For example, if your tune does not use Flex Fuel, all FF1/FF2 cells will be grey. No action is needed unless you intentionally enabled that feature.
Dual-ECU vehicles
Map validity reads only the master ECU. On first use you will see a one‑time prompt about this limitation; the slave ECU is not included in this check.