B2616

Code

Generic B — Body

Immobilizer Transponder Signal Fault

Brand: Generic

Type: B — Body

Views: UK: 9 EN: 26 RU: 9

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged or non-programmed key/transponder
Weak or dead battery in a key with remote/transponder battery
Faulty transponder antenna (coil) or antenna ring at the ignition lock
Broken, corroded, or loose wiring/connectors between antenna and immobilizer/BCM/ECM
Faulty immobilizer/transceiver module or BCM
Software/configuration error or corrupted immobilizer database (key IDs)

Symptoms

Engine will not crank or start (immobilizer prevents starter or fuel/ignition operation)
Starter cranks but engine does not fire
Security/immobilizer warning lamp illuminated or flashing
Intermittent starting problems that clear with a different key or after moving key position
No remote start or remote functions may be unaffected (depends on system)
Possible stored additional communication or EEPROM-related codes

What to check

Confirm code B2616 with a scan tool and note freeze-frame/related codes
Try a known-good or spare key to see if the fault follows the key
Check key battery (if applicable) and replace if low
Visually inspect antenna ring/coil at ignition lock for damage, corrosion, or loose mounting
Inspect wiring harness and connectors between antenna and immobilizer/BCM/ECM for continuity, corrosion, or water ingress
Verify immobilizer/BCM power and ground circuits are within specification

Signal parameters

Transponder systems commonly use low-frequency (LF) around 125 kHz for power/polling of passive transponders
Data modulation (ASK/FSK) sent from transponder is decoded by immobilizer — expected valid digital data pattern per manufacturer
Antenna/transceiver supply voltage should be present (typically vehicle low-voltage supply 5–12 V depending on design) and stable
Antenna coil continuity/resistance should be within manufacturer specification (check service manual)
Digital data line between transceiver and immobilizer/BCM should show valid logic levels (0/5V or CAN/serial messages as applicable)

Diagnostic algorithm

Verify and record stored DTC(s). Check for related codes (BCM/ECM/communication).
Attempt to start using a known-good or spare programmed key. If spare works, suspect original key/transponder.
If key uses a battery (integrated remote), check/replace the battery and retest.
Observe immobilizer/security lamp when key is presented and during crank; note abnormal lamp patterns.
Visually inspect antenna ring and ignition switch area for damage, foreign objects, or corrosion. Wiggle test connectors for intermittent faults.
With key in position, measure antenna coil continuity and resistance; compare to service specification. Check for short to ground or open circuit.
Probe power and ground at the transceiver/antenna module connector; verify proper supply voltages with key in position.
Use an oscilloscope or diagnostic tool capable of reading LF transponder signals to verify presence and quality of the 125 kHz carrier and modulated response when key is presented.
Check signal/data line between transceiver and immobilizer/BCM for proper logic levels or valid messages on serial/CAN bus. Repair wiring or connectors as needed.
If vehicle supports diagnostic key re-learn, attempt reprogramming/re-learning of key per manufacturer procedure; re-test with multiple keys.
If wiring, antenna, and keys are good but fault remains, consider replacement of the transceiver/antenna ring or immobilizer module and reprogram as required.
Clear codes and perform full start/drive cycle to confirm repair; monitor for recurrence and re-check related diagnostics if intermittent.

Likely causes

Key/transponder fault (missing or damaged transponder chip)
Antenna ring or antenna coil fault at the ignition barrel
Connector/cable fault or poor ground to immobilizer/transceiver
Intermittent fault due to corrosion or water damage
Immobilizer module or BCM hardware/software fault (less common)

Fault status

⚠️ Status

IMMOBILIZER TRANSPONDER SIGNAL FAULT — immobilizer/BCM/ECM did not detect a valid transponder response or detected an out-of-spec/intermittent transponder signal. Vehicle anti-theft system may prevent engine start.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours