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Home / DTC / U0111 — Lost Communication With Battery Energy Control Module A

U0111 — Lost Communication With Battery Energy Control Module A

Detailed page for trouble code U0111.

34,405codes
59brands
11,914generic
22,491specific
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U0111

Generic U — Network/User

Lost Communication With Battery Energy Control Module A

Brand: Generic
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in CAN/data bus wiring between BECM and other modules
  • Poor or intermittent BECM power or ground (fuse, relay, connector, battery voltage)
  • Corroded, loose or damaged connector at the BECM
  • Failed BECM (internal electronics)
  • Faulty module on the same data bus pulling the bus down
  • Incorrect or missing module software/calibration (after service update)

Symptoms

  • MIL/Warning indicator illuminated (HV/Battery/Service warnings)
  • HV battery management features disabled (charging, regen, charge control limited)
  • Reduced vehicle performance or limp mode
  • Battery or HV system warnings/messages in instrument cluster
  • Inability to read BECM parameters with a scan tool (no response)
  • Other modules reporting related U-codes (indicating network issues)

What to check

  • Connect a scan tool and record freeze frame, pending and permanent codes; attempt to communicate with BECM A
  • Check vehicle battery voltage (key on, engine off) — should be ~12–14V; verify good battery state
  • Verify fuses and relays for BECM power circuits; check for presence of ignition and B+ at module power pins
  • Visually inspect BECM connector and wiring for damage, corrosion, bent pins, or water intrusion
  • Check for other U-codes that indicate wider CAN bus failure (U0073, U0100, U0141, etc.)
  • Measure CAN bus continuity and resistance between CAN_H and CAN_L at multiple points; check for correct termination resistance (~60 ohm across H-L at two-term device, or ~120 ohm single)

Signal parameters

  • Key on, engine off battery supply to BECM: ~11–14 V measured at module power pin
  • Ground(s): near 0 V with low resistance to chassis ground
  • CAN bus idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (differential ≈ 0 V)
  • CAN bus dominant: CAN_H ≈ 3.5–3.9 V, CAN_L ≈ 1.1–1.5 V (differential ≈ 2.0 V)
  • Typical CAN bus baud rates: 500 kb/s or 250 kb/s depending on vehicle — verify with service data
  • Bus termination: combined resistance measured across CAN_H and CAN_L (system dependent) typically ~60 ohm (two 120 ohm terminators in parallel)

Diagnostic algorithm

  1. Read and record all DTCs and freeze frame data with a capable scan tool. Note if BECM is present/listed in module list.
  2. Attempt communication specifically with BECM A. Confirm “no response” status and note any related network errors.
  3. Verify vehicle battery voltage and state. If low, charge or raise to proper voltage before continuing.
  4. Inspect and test fuses and relays that supply BECM power. Verify B+ and switched ignition power at the BECM power pins with key ON.
  5. Inspect BECM connector: disengage, inspect pins for corrosion, damage, or pushed-out pins. Clean and reseat if necessary.
  6. With the scan tool monitoring the CAN bus, check for other modules responding. If no modules respond, suspect bus power/termination. If some respond and BECM does not, focus on wiring/connectors to BECM.
  7. Measure DC voltages at CAN_H and CAN_L at the BECM connector with key ON. Compare to expected idle values (~2.5 V) and check differential.
  8. Measure resistance/continuity of CAN_H and CAN_L back to a known-good module on the same bus. Check for short to battery or ground and for opens.
  9. If intermittent, perform wiggle testing on harness and connectors while monitoring bus traffic or using an oscilloscope to detect noise or signal loss.
  10. If wiring and power/ground are good, try to reflash or update BECM software per manufacturer procedure (some faults cleared by reprogramming).
  11. If failure persists and all wiring/power/ground/sw update checks are OK, consider replacing BECM A. After replacement or repair, clear codes and verify proper communication and vehicle function on road test.
  12. Document findings; if replacing modules, follow immobilizer or configuration pairing procedures as required by manufacturer.

Likely causes

  • Blown fuse or faulty BECM power/ignition relay preventing module turn-on
  • Damaged or corroded connector at the BECM causing intermittent contact
  • Short to ground or short to battery on CAN_H or CAN_L wiring
  • Failed BECM hardware (most likely if power/ground and bus wiring check OK)
  • Another module pulling CAN bus low/high or causing bus errors

Fault status

⚠️ Status
Lost Communication With Battery Energy Control Module A — no response from BECM A on the vehicle data bus (CAN).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-4.0 hours

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Code

U0111

HYUNDAI U — Network/User

Lost Communication With Battery Energy Control Module “A” | Lost Communication With Battery Energy Control Module “A” (C-CAN)

Brand: HYUNDAI
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in CAN/data bus wiring between BECM and other modules
  • Poor or intermittent BECM power or ground (fuse, relay, connector, battery voltage)
  • Corroded, loose or damaged connector at the BECM
  • Failed BECM (internal electronics)
  • Faulty module on the same data bus pulling the bus down
  • Incorrect or missing module software/calibration (after service update)

Symptoms

  • MIL/Warning indicator illuminated (HV/Battery/Service warnings)
  • HV battery management features disabled (charging, regen, charge control limited)
  • Reduced vehicle performance or limp mode
  • Battery or HV system warnings/messages in instrument cluster
  • Inability to read BECM parameters with a scan tool (no response)
  • Other modules reporting related U-codes (indicating network issues)

What to check

  • Connect a scan tool and record freeze frame, pending and permanent codes; attempt to communicate with BECM A
  • Check vehicle battery voltage (key on, engine off) — should be ~12–14V; verify good battery state
  • Verify fuses and relays for BECM power circuits; check for presence of ignition and B+ at module power pins
  • Visually inspect BECM connector and wiring for damage, corrosion, bent pins, or water intrusion
  • Check for other U-codes that indicate wider CAN bus failure (U0073, U0100, U0141, etc.)
  • Measure CAN bus continuity and resistance between CAN_H and CAN_L at multiple points; check for correct termination resistance (~60 ohm across H-L at two-term device, or ~120 ohm single)

Signal parameters

  • Key on, engine off battery supply to BECM: ~11–14 V measured at module power pin
  • Ground(s): near 0 V with low resistance to chassis ground
  • CAN bus idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (differential ≈ 0 V)
  • CAN bus dominant: CAN_H ≈ 3.5–3.9 V, CAN_L ≈ 1.1–1.5 V (differential ≈ 2.0 V)
  • Typical CAN bus baud rates: 500 kb/s or 250 kb/s depending on vehicle — verify with service data
  • Bus termination: combined resistance measured across CAN_H and CAN_L (system dependent) typically ~60 ohm (two 120 ohm terminators in parallel)

Diagnostic algorithm

  1. Read and record all DTCs and freeze frame data with a capable scan tool. Note if BECM is present/listed in module list.
  2. Attempt communication specifically with BECM A. Confirm “no response” status and note any related network errors.
  3. Verify vehicle battery voltage and state. If low, charge or raise to proper voltage before continuing.
  4. Inspect and test fuses and relays that supply BECM power. Verify B+ and switched ignition power at the BECM power pins with key ON.
  5. Inspect BECM connector: disengage, inspect pins for corrosion, damage, or pushed-out pins. Clean and reseat if necessary.
  6. With the scan tool monitoring the CAN bus, check for other modules responding. If no modules respond, suspect bus power/termination. If some respond and BECM does not, focus on wiring/connectors to BECM.
  7. Measure DC voltages at CAN_H and CAN_L at the BECM connector with key ON. Compare to expected idle values (~2.5 V) and check differential.
  8. Measure resistance/continuity of CAN_H and CAN_L back to a known-good module on the same bus. Check for short to battery or ground and for opens.
  9. If intermittent, perform wiggle testing on harness and connectors while monitoring bus traffic or using an oscilloscope to detect noise or signal loss.
  10. If wiring and power/ground are good, try to reflash or update BECM software per manufacturer procedure (some faults cleared by reprogramming).
  11. If failure persists and all wiring/power/ground/sw update checks are OK, consider replacing BECM A. After replacement or repair, clear codes and verify proper communication and vehicle function on road test.
  12. Document findings; if replacing modules, follow immobilizer or configuration pairing procedures as required by manufacturer.

Likely causes

  • Blown fuse or faulty BECM power/ignition relay preventing module turn-on
  • Damaged or corroded connector at the BECM causing intermittent contact
  • Short to ground or short to battery on CAN_H or CAN_L wiring
  • Failed BECM hardware (most likely if power/ground and bus wiring check OK)
  • Another module pulling CAN bus low/high or causing bus errors

Fault status

⚠️ Status
Lost Communication With Battery Energy Control Module A — no response from BECM A on the vehicle data bus (CAN).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-4.0 hours

Similar codes

U0100 U0073 U0141 U0121 U0155
371

Browse 371 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HYUNDAI

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+100 karma for a short comment :)
Keep it short and practical. Up to 500 characters.
Send to email
Code

U0111

LAND ROVER U — Network/User

Lost communication with battery power control module A

Brand: LAND ROVER
Type: U — Network/User
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Open or short in CAN/data bus wiring between BECM and other modules
  • Poor or intermittent BECM power or ground (fuse, relay, connector, battery voltage)
  • Corroded, loose or damaged connector at the BECM
  • Failed BECM (internal electronics)
  • Faulty module on the same data bus pulling the bus down
  • Incorrect or missing module software/calibration (after service update)

Symptoms

  • MIL/Warning indicator illuminated (HV/Battery/Service warnings)
  • HV battery management features disabled (charging, regen, charge control limited)
  • Reduced vehicle performance or limp mode
  • Battery or HV system warnings/messages in instrument cluster
  • Inability to read BECM parameters with a scan tool (no response)
  • Other modules reporting related U-codes (indicating network issues)

What to check

  • Connect a scan tool and record freeze frame, pending and permanent codes; attempt to communicate with BECM A
  • Check vehicle battery voltage (key on, engine off) — should be ~12–14V; verify good battery state
  • Verify fuses and relays for BECM power circuits; check for presence of ignition and B+ at module power pins
  • Visually inspect BECM connector and wiring for damage, corrosion, bent pins, or water intrusion
  • Check for other U-codes that indicate wider CAN bus failure (U0073, U0100, U0141, etc.)
  • Measure CAN bus continuity and resistance between CAN_H and CAN_L at multiple points; check for correct termination resistance (~60 ohm across H-L at two-term device, or ~120 ohm single)

Signal parameters

  • Key on, engine off battery supply to BECM: ~11–14 V measured at module power pin
  • Ground(s): near 0 V with low resistance to chassis ground
  • CAN bus idle (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (differential ≈ 0 V)
  • CAN bus dominant: CAN_H ≈ 3.5–3.9 V, CAN_L ≈ 1.1–1.5 V (differential ≈ 2.0 V)
  • Typical CAN bus baud rates: 500 kb/s or 250 kb/s depending on vehicle — verify with service data
  • Bus termination: combined resistance measured across CAN_H and CAN_L (system dependent) typically ~60 ohm (two 120 ohm terminators in parallel)

Diagnostic algorithm

  1. Read and record all DTCs and freeze frame data with a capable scan tool. Note if BECM is present/listed in module list.
  2. Attempt communication specifically with BECM A. Confirm “no response” status and note any related network errors.
  3. Verify vehicle battery voltage and state. If low, charge or raise to proper voltage before continuing.
  4. Inspect and test fuses and relays that supply BECM power. Verify B+ and switched ignition power at the BECM power pins with key ON.
  5. Inspect BECM connector: disengage, inspect pins for corrosion, damage, or pushed-out pins. Clean and reseat if necessary.
  6. With the scan tool monitoring the CAN bus, check for other modules responding. If no modules respond, suspect bus power/termination. If some respond and BECM does not, focus on wiring/connectors to BECM.
  7. Measure DC voltages at CAN_H and CAN_L at the BECM connector with key ON. Compare to expected idle values (~2.5 V) and check differential.
  8. Measure resistance/continuity of CAN_H and CAN_L back to a known-good module on the same bus. Check for short to battery or ground and for opens.
  9. If intermittent, perform wiggle testing on harness and connectors while monitoring bus traffic or using an oscilloscope to detect noise or signal loss.
  10. If wiring and power/ground are good, try to reflash or update BECM software per manufacturer procedure (some faults cleared by reprogramming).
  11. If failure persists and all wiring/power/ground/sw update checks are OK, consider replacing BECM A. After replacement or repair, clear codes and verify proper communication and vehicle function on road test.
  12. Document findings; if replacing modules, follow immobilizer or configuration pairing procedures as required by manufacturer.

Likely causes

  • Blown fuse or faulty BECM power/ignition relay preventing module turn-on
  • Damaged or corroded connector at the BECM causing intermittent contact
  • Short to ground or short to battery on CAN_H or CAN_L wiring
  • Failed BECM hardware (most likely if power/ground and bus wiring check OK)
  • Another module pulling CAN bus low/high or causing bus errors

Fault status

⚠️ Status
Lost Communication With Battery Energy Control Module A — no response from BECM A on the vehicle data bus (CAN).
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0-4.0 hours

Similar codes

U0100 U0073 U0141 U0121 U0155
320

Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

LAND ROVER

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

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