Why variance happens

24‑hour method (evidence trail)

Check Tool Pass/Fail rule
Odo & trip distance ECU/CAN vs GPS |Δ| ≤ 2% = ok
Refuel location/time Station geofence + card log Inside fence ±10 min = ok
Tank level jump Fuel sensor graph Rise ≈ liters purchased
Idle while refuel? Engine state Engine off preferred
Pattern repeat Exceptions queue 2+ anomalies → investigate

Tip: Keep a single “Fuel Evidence ID” per incident that links the card tx, GPS trip, and sensor chart.

Policy that works