THEFT Detected
Your vehicle's anti-theft system detected an unauthorized access attempt or security breach, like an alarm going off when someone tries the wrong key. The engine may not start or run properly until the security system is reset.
The ECU monitors transponder key authentication signals and compares them against stored security codes in the immobilizer module. If the key signal doesn't match the vehicle's security database or authentication fails, the ECU locks out fuel injection and ignition. The system also detects tamper attempts on security circuits and wiring.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Transponder Key Match | Valid key signal matches ECU database | Invalid or missing key authentication signal |
| Security Circuit Integrity | No tampering detected on immobilizer wiring | Broken or disconnected security module connections |
Code P1265 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, P1265 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.