Project
Safety
Read-only versus vehicle-changing operations.
Most Hanterill screens read information from the car. Clearing a fault code, resetting a control unit or starting a service routine can change it. The app separates those actions and asks for confirmation before sending them. This guide explains the limits of that protection.
This page explains what happens during read-only scans, how vehicle-changing actions are gated, and what safety precautions to follow when working on a car.
Reading is always the default#
Every normal scan, battery check, live telemetry chart, and inspection report in Hanterill is strictly read-only. During read-only operations, the app only sends messages that ask for information:
| Diagnostic action | What it does on the car |
|---|---|
| Open a diagnostic session | Wakes a module's diagnostic interface so it can answer sensor and identity questions |
| Read fault codes | Lists stored, pending, and permanent fault codes along with their freeze-frame snapshots |
| Read data values | Reads a live sensor value, counter, software version, or identity record |
| Read scaling information | Asks a module how a raw sensor number is scaled |
| Keep-alive heartbeat | Tells the module a scan is still running so it does not fall asleep mid-read |
| Read routine status | Checks the stored result of a routine without starting or stopping any actuator |
None of these messages alter any setting, calibration, adaptation value, or fault memory on your vehicle.
Vehicle-changing actions always ask first#
A diagnostic tool that cannot clear fault codes after a repair or retract the electronic parking brake for a pad change leaves the job unfinished. Hanterill includes those maintenance tools, and keeps them safe through clear boundaries:
- Explicit confirmation prompts: Every action that changes the car's state requires you to read a plain-language warning and confirm before a single command is sent.
- No firmware flashing or coding writes: Hanterill never flashes module firmware, never overwrites vehicle configuration or calibration memory, and never sends raw unverified write commands.
- Security-level protection: Vehicle manufacturers protect certain maintenance routines behind a module security lock (seed-and-key access). Hanterill can check in read-only mode whether a module's security levels are locked or unlocked, and clearly marks routines that are security-level protected on your vehicle.
What vehicle-changing actions cover
Vehicle-changing actions in Hanterill are limited to clearing stored fault codes, starting catalogued service and maintenance routines, and restarting an individual control unit. Even when a routine is available in the app, procedures such as steering-angle zeroing or camera/radar calibration must only be run when the car is set up according to the manufacturer's workshop procedure.
How fault-code clearing protects your diagnostic history#
Clearing fault codes is the most common write action. When you confirm a fault-code clear, Hanterill follows a careful six-step sequence so you never lose diagnostic evidence:
- Opens an extended session on each module, since vehicle modules ignore clear requests in their default state.
- Saves all freeze-frame snapshots first: Before erasing anything, Hanterill captures the freeze-frame conditions attached to existing fault codes into your local session archive.
- Sends the clear command across the selected modules.
- Waits for modules to finish internal housekeeping as they update their fault memory.
- Retries individual modules if the gateway was briefly busy during the broadcast clear.
- Re-reads every module and shows you a clear summary of which codes cleared and which stubborn codes remained active.
Optional module reset and driving-mode safety interlock#
If a module holds a latched code after a repair, you can optionally choose the force-reset follow-up, which restarts the affected module, waits roughly five seconds for it to reboot, and runs the clear pass once more.
For your safety, Hanterill checks the vehicle's operating mode first and refuses to reset any module if the car reports that it is in a driving state. Always keep the vehicle parked with the parking brake engaged during diagnostics.
Network traffic discipline and 12 V battery care#
An aggressive diagnostic tool can overwhelm a vehicle gateway or keep modules awake long after you walk away. Hanterill protects the car's network and 12-volt battery automatically:
- Paced request budgets: Multi-module sweeps pace their requests so the vehicle gateway is never flooded.
- Instant cancellation: You can stop any scan, sweep, or live recording immediately; Hanterill halts traffic between requests and cleans up any active periodic streams.
- Clean sleep release: As soon as a scan completes or you disconnect, Hanterill stops sending keep-alive heartbeats so every control unit can return to low-power sleep normally.
High-voltage safety on electric and hybrid vehicles#
High voltage is dangerous
Battery-electric and plug-in hybrid vehicles carry between 400 V and 800 V of direct current. Reading battery health or cell voltages in Hanterill does not de-energize the high-voltage system and does not make physical work on the battery pack, inverters, compressor, or orange high-voltage cables safe. Physical high-voltage service requires manufacturer training, insulated equipment, and a verified physical high-voltage disconnect procedure.
Independent software notice#
Hanterill is an independent diagnostic tool and is not affiliated with or endorsed by Volvo Cars, Polestar, Zeekr, Lynk & Co, or Geely. Never rely on a single diagnostic reading to make a safety-critical repair decision, especially when inspecting a platform or measurement marked as provisional.
What to do if a reading looks unusual#
If you see a fault code or sensor value you do not recognize, do not run a calibration or reset routine to try to clear it. Save the session, export a privacy-scrubbed support bundle, and compare the reading against a second scan before taking action.
Next#
- Service functions: the maintenance routines, their cautions, and security-level protection.
- Connection: safe cable setup and ignition states.
- DTC scanning: how fault scanning and freeze-frame preservation work.