B0101high severityBody
Immobilizer Transponder Signal Not Detected
on 2000 Toyota 4Runner 3.4L V6 · RWD
What this code means
The immobilizer system cannot detect the transponder signal from the key. The engine will not start.
Symptoms
- Engine cranks but will not start
- Security light flashing
- Key symbol on dashboard
- No-start condition
Common causes
- Dead key battery (smart key)
- Faulty transponder chip in key
- Damaged antenna ring around ignition
- Interference from other transponder keys
- Key handle cracked exposing transponder to damage
Diagnostic steps
- Try different registered key
- Hold key closer to ignition/start button
- Check for key battery (if applicable)
- Test antenna ring with known-good key
- Scan immobilizer codes
Repair notes
Replace key battery or have new key programmed. Replace antenna ring if faulty.
🔌 Don't have a code reader?
Any of these will read and clear this code — pick by how deep you want to go.
Budget handheld~$40
ANCEL AD410 →
No-phone-needed handheld — reads, clears, live data, freeze frame.
✓ ANCEL official store
Serious DIY~$100
BlueDriver Pro →
Enhanced codes (ABS, airbag, TPMS) plus repair reports.
SHOP FAVORITEShop-grade tablet~$300
Autel MaxiCOM MK808S →
Bidirectional tests, service resets, all systems.
✓ Autel official store
Pro diagnostics$1,500+
Autel MaxiSys MS906 Pro →
Full-system pro platform — topology mapping, ECU coding, the works.
✓ Autel official store
As an Amazon Associate and Autel/ANCEL partner, OLP earns from qualifying purchases — how we link. This never changes the specs we publish.
Other Body codes on this vehicle
B0001
Driver Frontal Stage 1 Deployment Control
B0002
Driver Frontal Stage 2 Deployment Control
B0003
Passenger Frontal Stage 1 Deployment Control
B0004
Passenger Frontal Stage 2 Deployment Control
B0005
Driver Knee Airbag Deployment Circuit
B0006
Passenger Knee Airbag Deployment Circuit
B0010
Driver Side Airbag Deployment
B0011
Driver Side Airbag Deployment Circuit Open
B0012
Driver Side Airbag Deployment Circuit Short to Ground
B0013
Driver Side Airbag Deployment Circuit Short to Battery