Diagnostics
Full vehicle diagnostics for FCA / Stellantis — DTC scan, topology and EOL decoding
FCA PROXI Tool is not only a configuration editor — it includes a full on-vehicle diagnostics module. Connect over an ELM327-compatible or J2534 adapter and scan the whole vehicle, read and clear fault codes, and find out exactly why a module rejected a configuration.
A full scan of every module on the vehicle
On connect the tool builds the module list from the vehicle's own configuration (the CAN-nodes that are actually present) and scans only what is really there — not a generic guess. You see each module, whether it answered, and its bus type.
Read and clear fault codes (DTCs)
Read stored and pending DTCs across the whole car in one pass, and clear them when the underlying issue is resolved. Codes are listed per module so you know where each fault lives.
Freeze-frame data
For logged faults the tool shows freeze-frame data — the conditions captured when the fault was set — so intermittent and condition-specific problems are easier to chase.
Module topology and bus map
See the vehicle's module topology and which bus each module sits on — including CAN-FD versus classic CAN. This tells you up front whether a module needs an FD-capable adapter to reach. More on adapters and CAN-FD.
EOL rejection-reason decoding — the differentiator
When a module rejects a configuration at end-of-line validation, most tools give you a raw code. FCA PROXI Tool decodes the rejection reason by parameter name — so you see which setting the module refused and why, not just that something failed. That turns a dead-end write into a clear next step.
On Vehicle vs All ECUs
Two views: On Vehicle shows only the modules actually present per the vehicle's configuration; All ECUs shows everything the body can have. Both are available in the OBD tab and in diagnostics — useful for retrofit planning and for confirming a module is present before you write.
How diagnostics fits with PROXI configuration
Scan the vehicle, fix the configuration, write it back over the same adapter, then re-scan to confirm the fault is gone and the modules agree. When a write is rejected, run a scan first — the EOL reason usually tells you what to change. See the PROXI alignment workflow.
FAQ
Does it scan and clear fault codes?
Yes. The built-in diagnostics module runs a full scan of every module present, reads and clears DTCs across the whole car, and shows freeze-frame data.
What is EOL rejection-reason decoding?
When a module rejects a configuration, the tool decodes the reason by parameter name, so you see which setting was refused and why instead of a raw code.
Do I need a special adapter for diagnostics?
An ELM327-compatible or J2534 adapter works. CAN-FD modules need an FD-capable adapter or driver. See the adapters guide.
Does it replace wiTECH or the OEM tool?
It includes full diagnostics and writes configuration directly, but it does not run the OEM flash/programming routine. For PROXI configuration, diagnostics and EU conversion it is a complete, standalone workflow.