TrueRoute

GPS Alert Appeared

TrueRoute monitors GPS signal quality and warns you when it detects possible disruption. If an alert appeared on your screen, here is what it means and what to do.

Alert types

Yellow warning banner

A yellow warning banner appears when the spoof confidence score exceeds 0.6. This means TrueRoute detects possible GPS disruption, but the signal is not yet untrusted. The app continues using GPS for positioning while monitoring the situation.

What to do: No action needed. Continue driving. The app is monitoring the situation and will switch to Dead Reckoning automatically if the score rises further.

yellow GPS disruption warning banner on the map screen

Red Dead Reckoning banner

A red banner appears when the spoof confidence score exceeds 0.8. GPS is now considered untrusted. The app has switched to Dead Reckoning mode and is navigating using your vehicle's OBD2 speed sensor and phone gyroscope instead of GPS.

What to do: Continue driving. Dead Reckoning maintains your position with less than 5% drift per 10 km when an OBD2 adapter is connected. The app returns to GPS automatically when the signal becomes trustworthy again.

red Dead Reckoning banner with orange position marker on map

How the confidence score works

TrueRoute calculates a spoof confidence score between 0.0 (GPS fully trusted) and 1.0 (GPS definitely disrupted). The score combines four detection methods:

  • Position jump detection: Flags sudden GPS position changes inconsistent with vehicle speed.
  • Speed mismatch detection: Compares GPS-derived speed against OBD2 speed.
  • Heading mismatch detection: Compares GPS heading against gyroscope heading.
  • GNSS anomaly detection: Identifies unusual satellite signal patterns.

The thresholds are:

  • 0.6 — Warning alert appears.
  • 0.8 — Dead Reckoning mode activates.
  • Below 0.3 for 30 continuous seconds — App returns to GPS-based positioning.

Common false positive causes

The GPS alert may appear in situations where GPS signal is degraded but not spoofed:

  • Tunnels and underpasses. GPS signal is blocked temporarily. The alert may appear briefly and resolve when you exit.
  • Underground parking garages. GPS signal is lost entirely. The alert resolves when you drive out.
  • Dense urban canyons. Tall buildings cause GPS multipath errors that can trigger the alert.
  • GPS signal loss at ignition. If the app starts before a GPS fix is acquired, the initial position may be inaccurate.

In these cases, the score drops below 0.3 and the alert clears automatically once GPS signal improves.

Check the confidence score in diagnostics

  1. Tap the Diagnostics icon in the main menu.

  2. Find the Spoof confidence score value. A score below 0.3 indicates GPS is trusted.

  3. Review the per-detector sub-scores to see which detector triggered the alert.

diagnostics screen showing spoof confidence score and sub-scores

Force GPS mode (manual override)

If you are confident your GPS is accurate despite the alert (for example, after exiting a tunnel), you can manually override the mode.

  1. Open Settings in TrueRoute.

  2. Tap Positioning Mode.

  3. Select Force GPS Mode. The app will use GPS regardless of the confidence score.

Warning: Only force GPS mode when you are certain the signal is trustworthy. Forcing GPS during actual spoofing will result in incorrect positioning.

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