PATS Received Invalid Format Of Key-Code From Ignition Key Transponder
Your car's security system (PATS) can't read the unique code from your key's transponder chip, like a lock that doesn't recognize the correct key pattern. The engine won't start or may stall because the car thinks you're using an unauthorized key.
The Powertrain Control Module expects to receive a valid 40-bit encrypted security code from the ignition key transponder within milliseconds of key insertion. The PATS receiver module decodes this RF signal and compares it against programmed vehicle keys. If the data format is corrupted, incomplete, or unrecognizable, the ECU blocks fuel injection and ignition.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| Transponder Signal Format | Valid 40-bit encrypted code received and verified | Invalid, corrupted, or unrecognizable code format detected |
| Signal Reception Quality | Signal strength sufficient and data integrity verified | Weak signal, noise interference, or checksum mismatch |
Code B1602 is a low-severity fault. Your vehicle is generally safe to drive to a workshop for diagnosis. However, do not ignore it indefinitely — low-severity codes often indicate developing problems that become expensive if neglected. Book a diagnostic appointment within 2–4 weeks. If you notice any additional symptoms (rough running, power loss, unusual smells), treat it as higher priority.
Once the fault is repaired, B1602 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.