Vehicle Security System - Invalid Key
The key or fob used in the ignition doesn't match the vehicle's security system.
Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.
What it means (plain English)
When you try to start the car, the security system checks if the key is programmed to the vehicle. If it doesn't recognize the key, it won't allow the engine to start.
What the computer is actually seeing
The vehicle's security module detects a key signal that doesn't match the stored key codes in its memory.
What a healthy reading looks like
The key should send a signal with a specific frequency and identifier that matches what's programmed in the vehicle (usually around 315 MHz for RF keys).
Guided diagnostic — the DiagCoach way
Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.
- 11. Inspect the key for visible damage or wear. Decision point: Is the key damaged? (Yes: Replace key. No: Proceed to step 2.)
- 22. Test the key battery voltage. Expected: At least 3 volts. Decision point: Is voltage good? (No: Replace battery. Yes: Proceed to step 3.)
- 33. Check for any physical obstructions in the ignition lock. Decision point: Any obstruction found? (Yes: Clear obstruction. No: Continue to step 4.)
- 44. Scan for other related diagnostic trouble codes (DTCs). Decision point: Are there other security-related codes present? (Yes: Diagnose those codes first. No: Proceed to step 5.)
- 55. Inspect the wiring and connectors between the ignition switch and the vehicle security module. Decision point: Any damage observed? (Yes: Repair wiring. No: Replace vehicle security module.)
Common causes
- Faulty key or fob
- Weak key battery
- Interference from other electronic devices
- Faulty ignition lock cylinder
- Damaged wiring or connectors in the key system
Typical repair cost
$$
Related codes
Frequently asked questions
Is it safe to drive if this code appears?
No, the vehicle may not start or could die while driving due to the security system preventing engine operation.
Will the code come back after clearing it?
Yes, if the underlying issue isn't resolved, the code can return.
Why does this code pair with other codes?
It often indicates issues with the security system as a whole; multiple codes can point towards a systemic problem.
Working a real vehicle right now?
Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.
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