Toggle Side Panel

Shopping Cart

No products in the basket.

Shopping Cart

No products in the basket.

Close search
Home / DTC / B2406 — STL.unit comm.(PTC operate)

B2406 — STL.unit comm.(PTC operate)

Detailed page for trouble code B2406.

33,912codes
59brands
11,451generic
22,461specific
All codes P-codes (Powertrain) B-codes (Body) C-codes (Chassis) U-codes (Network/User) Tesla Alerts
Reset
Code

B2406

MITSUBISHI B — Body

STL.unit comm.(PTC operate)

Brand: MITSUBISHI
Type: B — Body
Views: UK: 16 EN: 23 RU: 22
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short or intermittent wiring between modules (power, ground or communication lines)
  • Faulty connector (corrosion, bent pins, poor contact)
  • Failed STL/PTC control unit or related HVAC/BCM module
  • Blown fuse or faulty relay supplying PTC/STL unit
  • CAN/LIN bus wiring fault or missing termination
  • Battery voltage too low during attempt to operate PTC

Symptoms

  • PTC (auxiliary) heater does not activate when commanded
  • HVAC takes longer to produce heat or reduced cabin heating
  • Related warning lamp or message on dash (HVAC/aux heater)
  • Stored B2406 code and possibly other communication DTCs
  • Erratic operation of HVAC or automatic climate control functions

What to check

  • Read freeze frame and full DTC list with a capable scan tool; note any other communication codes
  • Verify battery voltage is within normal range (engine off and cranking conditions)
  • Inspect fuses and relays for PTC/STL and HVAC/BCM circuits
  • Visually inspect connectors and harnesses at the STL/PTC unit and associated modules for corrosion, damage or loose pins
  • Check for activity on the vehicle communication bus (CAN/LIN) with a scan tool or oscilloscope
  • Measure supply voltage and ground continuity at the STL/PTC unit connector

Signal parameters

  • Supply voltage to STL/PTC unit: nominal battery voltage ~11–14.5 V when engine running
  • Ground: continuity to chassis ground, resistance should be very low (
  • CAN bus idle differential: both lines ~2.5 V nominal with expected differential behavior during communication (use scope/scan tool)
  • LIN bus idle: typically near battery voltage with pull-down signaling (verify with vehicle-specific reference)
  • PTC heater current draw: can be high when active (tens of amps depending on heater design) — verify using appropriate in-line current measurement
  • PTC element resistance: low ohms (measure against manufacturer spec in service literature)

Diagnostic algorithm

  1. Connect a diagnostic scan tool, read and record all related DTCs and freeze frame data. Clear codes and attempt to reproduce.
  2. Verify battery condition and voltage. Recharge or replace if low and repeat test.
  3. Check fuses/relays for PTC/STL and HVAC circuits; replace if faulty.
  4. Inspect and secure connectors at the STL/PTC unit, HVAC control module and BCM. Repair corrosion or damaged pins.
  5. With the scan tool, attempt to command the PTC on/off while monitoring module responses and communication bus traffic.
  6. Check power and ground at the STL/PTC unit connector with meter; repair any open circuits.
  7. Probe CAN/LIN lines with a scope or breakout box: confirm idle voltages, data frames and proper termination (approx. 60 Ω across CANH/CANL for CAN bus).
  8. Measure PTC heater resistance and, if safe and specified, measure current draw during operation. Compare to service specifications.
  9. Perform continuity and short checks on the wiring harness between relevant modules. Repair any damaged wiring.
  10. If wiring and power/ground are good but communication is absent or corrupted, consider replacing the STL/PTC control unit or the communicating module per service manual. Reprogram/relearn as required.
  11. After repairs, clear codes and verify normal operation through several test cycles; monitor for reappearance of B2406 or related codes.

Likely causes

  • Loose or corroded connector at the STL/PTC unit
  • Open or short on CAN or LIN communication line to the STL unit
  • Failed STL/PTC control unit
  • Missing 12 V supply or ground to the STL/PTC unit (faulty fuse/relay)
  • Intermittent wiring harness damage (chafing, water intrusion)

Fault status

⚠️ Status
Communication error: STL unit did not respond or communication failed while PTC heater operation was requested. Check power, ground, connectors, wiring and network communications.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

B2400 B2401 B2402 B2403 B2405 B2407
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
Code

B2406

Other B — Body

Audio Single-Disc CD Player Internal Fault

Brand: Other
Type: B — Body
Views: UK: 20 EN: 36 RU: 25
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open, short or intermittent wiring between modules (power, ground or communication lines)
  • Faulty connector (corrosion, bent pins, poor contact)
  • Failed STL/PTC control unit or related HVAC/BCM module
  • Blown fuse or faulty relay supplying PTC/STL unit
  • CAN/LIN bus wiring fault or missing termination
  • Battery voltage too low during attempt to operate PTC

Symptoms

  • PTC (auxiliary) heater does not activate when commanded
  • HVAC takes longer to produce heat or reduced cabin heating
  • Related warning lamp or message on dash (HVAC/aux heater)
  • Stored B2406 code and possibly other communication DTCs
  • Erratic operation of HVAC or automatic climate control functions

What to check

  • Read freeze frame and full DTC list with a capable scan tool; note any other communication codes
  • Verify battery voltage is within normal range (engine off and cranking conditions)
  • Inspect fuses and relays for PTC/STL and HVAC/BCM circuits
  • Visually inspect connectors and harnesses at the STL/PTC unit and associated modules for corrosion, damage or loose pins
  • Check for activity on the vehicle communication bus (CAN/LIN) with a scan tool or oscilloscope
  • Measure supply voltage and ground continuity at the STL/PTC unit connector

Signal parameters

  • Supply voltage to STL/PTC unit: nominal battery voltage ~11–14.5 V when engine running
  • Ground: continuity to chassis ground, resistance should be very low (
  • CAN bus idle differential: both lines ~2.5 V nominal with expected differential behavior during communication (use scope/scan tool)
  • LIN bus idle: typically near battery voltage with pull-down signaling (verify with vehicle-specific reference)
  • PTC heater current draw: can be high when active (tens of amps depending on heater design) — verify using appropriate in-line current measurement
  • PTC element resistance: low ohms (measure against manufacturer spec in service literature)

Diagnostic algorithm

  1. Connect a diagnostic scan tool, read and record all related DTCs and freeze frame data. Clear codes and attempt to reproduce.
  2. Verify battery condition and voltage. Recharge or replace if low and repeat test.
  3. Check fuses/relays for PTC/STL and HVAC circuits; replace if faulty.
  4. Inspect and secure connectors at the STL/PTC unit, HVAC control module and BCM. Repair corrosion or damaged pins.
  5. With the scan tool, attempt to command the PTC on/off while monitoring module responses and communication bus traffic.
  6. Check power and ground at the STL/PTC unit connector with meter; repair any open circuits.
  7. Probe CAN/LIN lines with a scope or breakout box: confirm idle voltages, data frames and proper termination (approx. 60 Ω across CANH/CANL for CAN bus).
  8. Measure PTC heater resistance and, if safe and specified, measure current draw during operation. Compare to service specifications.
  9. Perform continuity and short checks on the wiring harness between relevant modules. Repair any damaged wiring.
  10. If wiring and power/ground are good but communication is absent or corrupted, consider replacing the STL/PTC control unit or the communicating module per service manual. Reprogram/relearn as required.
  11. After repairs, clear codes and verify normal operation through several test cycles; monitor for reappearance of B2406 or related codes.

Likely causes

  • Loose or corroded connector at the STL/PTC unit
  • Open or short on CAN or LIN communication line to the STL unit
  • Failed STL/PTC control unit
  • Missing 12 V supply or ground to the STL/PTC unit (faulty fuse/relay)
  • Intermittent wiring harness damage (chafing, water intrusion)

Fault status

⚠️ Status
Communication error: STL unit did not respond or communication failed while PTC heater operation was requested. Check power, ground, connectors, wiring and network communications.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-3.0 hours

Similar codes

B2400 B2401 B2402 B2403 B2405 B2407
6,477

The library contains 6,477 repair and diagnostic manuals. Choose a brand to open the full manual tree by year, model and trim.

AUDI
1,160
DAEWOO
75
FIAT
26
GENESIS
207
HUMMER
138
HYUNDAI
371
ISUZU
86
LAND ROVER
320
LEXUS
1
LINCOLN
166
MERCEDES-BENZ
610
MERCURY
296
MITSUBISHI
406
PORSCHE
136
TESLA
58
TOYOTA
2,042
TRIUMPH
131
VOLKSWAGEN
139
VOLVO
109
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 .