Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / B1A0F — Keyless/KOS key 8 performance

B1A0F — Keyless/KOS key 8 performance

Detailed page for trouble code B1A0F.

34,405codes
59brands
11,914generic
22,491specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

B1A0F

MITSUBISHI B — Body

Keyless/KOS key 8 performance

Brand: MITSUBISHI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Weak or dead key fob battery
  • Damaged or faulty key transponder/module
  • Poor RF signal or antenna/receiver fault in vehicle
  • Intermittent wiring or connector problem between antenna and KOS control unit
  • Key not properly registered or corrupted key data
  • CAN/bus communication errors or BCM/KOS module fault

Symptoms

  • “Key not detected” or similar message on dash when using that specific key
  • Intermittent or no push-button start / engine does not start with that key
  • Keyless entry (lock/unlock) fails or is unreliable with that key
  • Immobiliser or security warning lamp illuminated
  • Other keys work normally while key 8 fails
  • Long crank or no crank condition when trying to start with that key

What to check

  • Verify the fault is repeatable and identify which key(s) reproduce the code
  • Check battery voltage in key 8 and replace with a known-good battery
  • Try a different registered key to confirm vehicle-side vs key-side issue
  • Scan all modules for additional related DTCs (BCM, immobiliser, CAN bus)
  • Inspect antenna(s)/receiver modules and wiring for damage, corrosion, or loose connectors
  • Check for obvious RF interference sources near vehicle during test

Signal parameters

  • Key internal battery voltage (V)
  • Transponder ID read status (OK/FAIL)
  • Received RF signal strength / RSSI (if available)
  • Rolling code synchronization / learn count
  • KOS module receive error rate or timeout counts
  • CAN frames for key authentication and their timestamps

Diagnostic algorithm

  1. Reproduce the symptom: confirm B1A0F is current and note conditions (distance, engine off/on, doors open/closed).
  2. Check and replace the key battery in key 8; retest to see if code clears.
  3. Verify other registered keys function correctly. If they do, focus on the failing key hardware/data.
  4. Use a diagnostic tool to read key ID and registration status; attempt to re-register or re-learn key 8 per service procedure.
  5. Inspect and test keyless antenna(s) and connectors (driver door, front passenger, start button area, luggage) for continuity and secure connections.
  6. With a scan tool, monitor KOS/BCM messages and look for timeouts, CRC errors, or missing authentication frames when the key is presented.
  7. Check for related DTCs (BCM, immobiliser, CAN U-codes). Repair any identified wiring or module communication faults.
  8. If antenna and wiring are good but key still fails, try cloning/using a known-good key head or replace the key fob and reprogram.
  9. If multiple keys or vehicle-side units fail, consider replacing or reflashing the keyless control module/BCM per manufacturer guidance.
  10. Clear codes and perform full retest. Advise customer about spare key replacement or programming if required.

Likely causes

  • Low battery in the reported key fob
  • Antenna or keyless receiver near starter/door not detecting key 8
  • Faulty key transponder hardware (internal damage)
  • Faulty connector or wiring to the keyless control module
  • Key registration data corrupted or missing for key slot 8

Fault status

⚠️ Status
Keyless/KOS key 8 performance — vehicle reports unreliable or failed detection/authentication of registered key #8.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

B1A0E B1A10 U0140 U0100 B1600
406

Browse 406 MITSUBISHI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

MITSUBISHI

Your experience will help others
+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email

Report

Harassment or bullying behavior
Contains mature or sensitive content
Contains misleading or false information
Contains abusive or derogatory content
Contains spam, fake content or potential malware

Block Member?

Please confirm you want to block this member.

You will no longer be able to:

  • See blocked member's posts
  • Mention this member in posts
  • Invite this member to groups
  • Message this member
  • Add this member as a connection

Please note: This action will also remove this member from your connections and send a report to the site admin. Please allow a few minutes for this process to complete.

Report

You have already reported this .