Lexus Blind Spot Monitor Inoperative (DTC C1AB413 / C1AB513) Explained
Lexus has released Technical Service Bulletin L-SB-0024-25 (Canada: L-TCI-6057) addressing Blind Spot Monitor (BSM) failures and malfunction warning messages on 2023-2025 RX and 2024-2025 TX models, associated with Diagnostic Trouble Codes (DTC) C1AB413 and C1AB513.
Good News: Radar Sensors & Mirrors Are NOT Blown — Free TSB Software Update
If your Lexus BSM light is disabled or throwing DTC C1AB413 / C1AB513, do NOT pay out of pocket to replace expensive radar sensors ($1,500+). Under Lexus TSB L-SB-0024-25 (Canada: L-TCI-6057), this is a 100% software threshold bug covered under the Lexus Basic Warranty (48 Months / 50,000 Miles or 80,000 km). Act before your 4-year warranty runs out!
Symptoms & Conditions
- • Blind Spot Monitor (BSM) system becomes inoperative or intermittently fails to detect vehicles.
- • 'BSM Malfunction' warning message displayed on the Multi-Information Display (MID).
- • Driving Assist Information indicator lamp illuminated on the instrument cluster.
- • DTC C1AB413 present: Outer Mirror Indicator (Module 'B' Side) Circuit Open.
- • DTC C1AB513 present: Outer Mirror Indicator (Module 'A' Side) Circuit Open.
The Root Cause (Master Tech Diagnosis)
The issue is caused by overly sensitive BSM radar sensor software that incorrectly detects an open circuit in the outer rearview mirror LED indicator wiring. The physical wiring, mirror glass, and radar sensors are completely intact, but the software falsely triggers the malfunction code and disables the blind spot detection system.
Master Tech Insider Warnings
Crucial information every Lexus owner needs to know before going to the dealership
30% to 40% of All Scanned RX & TX Vehicles Have This Fault
From hands-on dealership diagnostic experience: nearly 3 to 4 out of every 10 RX and TX vehicles scanned in the service bay show stored C1AB413 or C1AB513 codes, even when the owner hasn't noticed an obvious warning light yet. It is one of the most widespread software glitches in recent Lexus production.
Crucial Dealership Tip: Act BEFORE Your 4-Year Warranty Expires
Unlike powertrain or emission warranties that last 8 years, this BSM repair is covered under the Lexus Basic Warranty: only 48 Months / 50,000 Miles (US) or 48 Months / 80,000 Kilometers (Canada). Once your basic warranty expires, dealerships will charge $250 to $400 for labor to flash the sensors! When you take your car in for regular service, tell your service advisor: 'My Blind Spot Monitor intermittently fails to light up.' The technician will scan for codes, find C1AB413/C1AB513, and perform the free TSB update.
DO NOT Replace the Expensive BSM Sensors ($1,500+ Saved)
The TSB explicitly states: 'The Blind Spot Monitor (BSM) sensors (P/N 88162-xxxxx) should NOT be replaced as part of the Repair Procedure.' Independent shops frequently misdiagnose C1AB413/C1AB513 as a blown radar sensor behind the bumper. It is purely a software calibration bug.
💻 Official Factory ECU Calibration Details
Your dealership technician will connect Toyota/Lexus GTS+ (Techstream) and flash reprogram BOTH Blind Spot Monitor sensors (Sensor 'A' and Sensor 'B') with updated calibration files:
| Engine Application | Calibration Number | Previous (Buggy) Calibration ID | New (Updated) Calibration ID |
|---|---|---|---|
| RX 350/350h/500h & TX 350/500h/550h+ | BSM Sensor A | 8816F0E03000 / 8816F4002000 / 8816F4817600 | 8816F5805100 (or 8816F5005100) |
| RX 350/350h/500h & TX 350/500h/550h+ | BSM Sensor B | 8816F0E03000 / 8816F4002000 / 8816F4817600 | 8816F5805100 (or 8816F5005100) |
🔧 Recommended OBD2 Scanners for BSM Diagnostics
Verify hidden C1AB413/C1AB513 fault codes before scheduling your dealership service
Autel MaxiAP AP200 Bluetooth OBD2 Scanner (All Systems Diagnostic)
Scan your own Lexus for hidden C1AB413 and C1AB513 BSM codes from your smartphone before your 4-year factory warranty expires so you can demand the free TSB update.
NOCO Genius5 6V/12V 5-Amp Smart Battery Charger & Maintainer
Maintains 13.5V clean power during ECU reflashes and prevents low-voltage bus communication errors on modern electronic Lexus platforms.
TEKTON 1/2-Inch Drive Click Torque Wrench (10-150 ft-lb)
Factory accuracy torque wrench for wheel lug fasteners and chassis maintenance on 2023+ RX and TX models.
❓ Frequently Asked Questions About TSB L-SB-0024-25
What causes DTC C1AB413 and C1AB513 on Lexus RX and TX?
DTC C1AB413 and C1AB513 represent a false 'circuit open' error detected by the Blind Spot Monitor radar sensors. Due to overly strict sensor software thresholds, the BSM ECU misinterprets normal electrical resistance variations in the side mirror LED indicator as an open circuit, shutting down the BSM system.
How long is TSB L-SB-0024-25 covered under warranty?
This repair is covered under the Lexus Basic Warranty for 48 months or 50,000 miles (80,000 kilometers in Canada), whichever occurs first. Because this is shorter than the 8-year powertrain/emission warranty, owners should request this update before their 4-year warranty runs out.
How do I get the dealer to perform TSB L-SB-0024-25 for free?
During your next routine maintenance visit before your 48-month warranty expires, mention to your service advisor: 'My Blind Spot Monitor intermittently stops working or fails to light up in the mirrors.' The technician will scan the BSM system, retrieve the stored C1AB413/C1AB513 code, and flash reprogram both BSM sensors under warranty at no cost.
Do the BSM radar sensors need to be replaced?
No. The official Lexus bulletin explicitly instructs technicians NOT to replace the BSM sensors (P/N 88162-xxxxx). The issue is 100% resolved by updating the sensor calibration firmware.