Smart Key Diagnostics

PKES (Passive Keyless Entry & Start) diagnostics — using a Flipper Zero and DiagFlow to systematically diagnose “key not detected” complaints. No more guessing.

Tech gets a “key not detected” complaint. Right now they’re guessing — is it the fob battery? The antenna? The KVM? With a Flipper Zero and a simple diagnostic workflow, you can narrow it down in minutes.

This is diagnostics, not guessing. Follow the process.

The Diagnostic Workflow

A step-by-step approach to smart key diagnostics:

Check Fob Battery Voltage

Start simple. A weak battery is the #1 cause of smart key complaints.

Capture Fob Signal (Sub-GHz)

Flipper Sub-GHz scan — is the fob transmitting at 315 or 433 MHz? Log the result.

Check LF Antenna Response (125/134 KHz)

Flipper detects if LF antennas are broadcasting the wake-up signal — check doors, trunk, interior.

Verify Authentication Handshake

Fob responds to LF wake-up, car responds to fob — does the handshake complete?

Narrow to Component

Fob works + antennas work = KVM or RF receiver problem. Fob dead = fob. Antennas dead = wiring or module.

Flipper-Testable Components

LF Transmitters

125/134 KHz — Flipper detects if antennas are broadcasting the wake-up signal

Smart Key Fob

Sub-GHz scan verifies the key is responding at 315/433 MHz

RF Receiver

If the key is transmitting but the car doesn’t respond — problem is likely here or KVM

CAN Bus Modules

ABS, TCM, KVM, Security, ECM, Cluster, Steering Lock — Flipper with CAN GPIO board can sniff traffic

Frequency Reference

Common smart key frequencies by region and make:

Region / Make	Frequency	Notes
Most US Vehicles	315 MHz	Standard North American frequency
JLR (Jaguar/Land Rover)	433 MHz	European standard
European (BMW, Mercedes, VW)	433 MHz	EU regulation frequency
Japanese (Toyota, Honda)	315 MHz (US)	May vary by market
LF Wake-up (all)	125/134 KHz	Universal for PKES antenna wake-up

Captures and Gallery

Flipper captures and diagnostic screenshots will be added here as the tool develops.

Flipper Zero — Signal Viewer

First capture — more signal captures coming.

More captures coming — check back often

Have a smart key diagnostic to share? Send it in