Code
U0242
Generic
U — Network/User
Lost Communication With Headlamp Control Module B
Views:
UK: 24
EN: 25
RU: 21
AI status
Completed
Completed
100%
Causes
- Faulty or missing power/ground to the headlamp control module B
- Damaged, corroded, or disconnected wiring or connectors (including CAN bus lines)
- Blown fuse or failed relay supplying the module
- CAN bus fault (open, short to battery/ground, improper termination)
- Failed headlamp control module B (internal electronics or firmware)
- Software or calibration mismatch after module replacement or update
Symptoms
- Driver information/warning lamp or message about headlamp/module communication
- Headlamp B inoperative, stuck, flickering, or not responding to controls
- Reduced or no automatic headlamp function for that side (if applicable)
- Related systems showing reduced functionality or additional communication DTCs
- Possible loss of CAN bus messages to other modules (intermittent)
What to check
- Connect a diagnostic scan tool; read and record U0242 and any related network DTCs
- Check vehicle battery voltage and charging system (stable 12–14.5 V during test)
- Visually inspect wiring, connectors, and grommets for damage, corrosion, or water ingress at the module and along harness
- Verify module power and ground with a multimeter at the module connector
- Check relevant fuses and relays for the headlamp/module circuit
- Measure CAN bus voltages and termination resistance (check CANH/CANL idle and dominant voltages and ~60 Ω across bus)
Signal parameters
- Vehicle battery: nominal 12–14.5 V with engine running
- CAN bus idle voltages: CANH ≈ 2.5 V, CANL ≈ 2.5 V (approx. equal); dominant state: CANH ≈ 3.5 V, CANL ≈ 1.5 V
- CAN bus differential (dominant) ≈ 2.0 V; termination resistance ≈ 60 Ω across CANH–CANL
- Module power pin ≈ battery voltage with ignition ON; ground pin ≈ 0 V
- Expected message frequency: periodic headlamp status messages typically repeat (varies by manufacturer) — absence indicates lost comms
Diagnostic algorithm
- Use a scan tool to confirm U0242 and note any additional U0xxx or B/C/P codes. Record freeze-frame and occurrence conditions.
- Verify battery voltage is within specification. Low voltage can cause network and module faults.
- Visually inspect the headlamp control module B and harness for damage, corrosion, moisture, or loose connectors. Repair or secure connectors as needed.
- Check and verify fuses/relays that feed the headlamp control module; replace if blown.
- With ignition ON, measure power and ground at the module connector. Repair any open or high-resistance circuits.
- Measure CANH and CANL at the module connector with a multimeter/scope. Confirm idle and dominant levels and check for ~60 Ω termination. If voltages are out of range, trace wiring toward the bus and inspect for shorts or opens.
- If bus voltages are normal, use a scope or capable scan tool to look for valid CAN frames from module B. If no frames, inspect module-side wiring and connector pins for continuity to the bus and other nodes.
- Perform wiggle and connector cleaning tests while monitoring the network for changes. Repair or replace damaged wiring/harness sections.
- If a single module is causing bus errors (bus-off), disconnect the module (if safe and recommended by manufacturer) to see if network returns to normal. Use caution with lamps that use high-voltage drivers; isolate power before disconnecting.
- If wiring, power, and bus appear good but the module does not communicate, consult manufacturer service information for reprogramming or module replacement. Replace the module only after verifying wiring and network integrity.
- Clear codes and perform a road/test verification of the system. Re-scan to confirm resolution.
Likely causes
- Loose/corroded connector at headlamp control module B
- Open or shorted CAN-H or CAN-L wiring near the module
- Blown module fuse or bad power feed
- Module has entered bus-off state due to repeated errors
- Module internal failure after water intrusion or impact
Fault status
Status
Lost communication with Headlamp Control Module B — module not responding on vehicle network (CAN).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop Manual199,00 UAH
Audi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop Manual199,00 UAH
AUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop Manual199,00 UAH
Audi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop Manual199,00 UAH
Audi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop Manual199,00 UAH
Audi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop Manual199,00 UAH
Audi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop Manual199,00 UAH
Audi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop Manual199,00 UAH
LAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
Code
U0242
HYUNDAI
U — Network/User
Lost Communication With Headlamp Control Module “B”
Views:
UK: 20
EN: 19
RU: 20
AI status
Completed
Completed
100%
Causes
- Faulty or missing power/ground to the headlamp control module B
- Damaged, corroded, or disconnected wiring or connectors (including CAN bus lines)
- Blown fuse or failed relay supplying the module
- CAN bus fault (open, short to battery/ground, improper termination)
- Failed headlamp control module B (internal electronics or firmware)
- Software or calibration mismatch after module replacement or update
Symptoms
- Driver information/warning lamp or message about headlamp/module communication
- Headlamp B inoperative, stuck, flickering, or not responding to controls
- Reduced or no automatic headlamp function for that side (if applicable)
- Related systems showing reduced functionality or additional communication DTCs
- Possible loss of CAN bus messages to other modules (intermittent)
What to check
- Connect a diagnostic scan tool; read and record U0242 and any related network DTCs
- Check vehicle battery voltage and charging system (stable 12–14.5 V during test)
- Visually inspect wiring, connectors, and grommets for damage, corrosion, or water ingress at the module and along harness
- Verify module power and ground with a multimeter at the module connector
- Check relevant fuses and relays for the headlamp/module circuit
- Measure CAN bus voltages and termination resistance (check CANH/CANL idle and dominant voltages and ~60 Ω across bus)
Signal parameters
- Vehicle battery: nominal 12–14.5 V with engine running
- CAN bus idle voltages: CANH ≈ 2.5 V, CANL ≈ 2.5 V (approx. equal); dominant state: CANH ≈ 3.5 V, CANL ≈ 1.5 V
- CAN bus differential (dominant) ≈ 2.0 V; termination resistance ≈ 60 Ω across CANH–CANL
- Module power pin ≈ battery voltage with ignition ON; ground pin ≈ 0 V
- Expected message frequency: periodic headlamp status messages typically repeat (varies by manufacturer) — absence indicates lost comms
Diagnostic algorithm
- Use a scan tool to confirm U0242 and note any additional U0xxx or B/C/P codes. Record freeze-frame and occurrence conditions.
- Verify battery voltage is within specification. Low voltage can cause network and module faults.
- Visually inspect the headlamp control module B and harness for damage, corrosion, moisture, or loose connectors. Repair or secure connectors as needed.
- Check and verify fuses/relays that feed the headlamp control module; replace if blown.
- With ignition ON, measure power and ground at the module connector. Repair any open or high-resistance circuits.
- Measure CANH and CANL at the module connector with a multimeter/scope. Confirm idle and dominant levels and check for ~60 Ω termination. If voltages are out of range, trace wiring toward the bus and inspect for shorts or opens.
- If bus voltages are normal, use a scope or capable scan tool to look for valid CAN frames from module B. If no frames, inspect module-side wiring and connector pins for continuity to the bus and other nodes.
- Perform wiggle and connector cleaning tests while monitoring the network for changes. Repair or replace damaged wiring/harness sections.
- If a single module is causing bus errors (bus-off), disconnect the module (if safe and recommended by manufacturer) to see if network returns to normal. Use caution with lamps that use high-voltage drivers; isolate power before disconnecting.
- If wiring, power, and bus appear good but the module does not communicate, consult manufacturer service information for reprogramming or module replacement. Replace the module only after verifying wiring and network integrity.
- Clear codes and perform a road/test verification of the system. Re-scan to confirm resolution.
Likely causes
- Loose/corroded connector at headlamp control module B
- Open or shorted CAN-H or CAN-L wiring near the module
- Blown module fuse or bad power feed
- Module has entered bus-off state due to repeated errors
- Module internal failure after water intrusion or impact
Fault status
Status
Lost communication with Headlamp Control Module B — module not responding on vehicle network (CAN).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email
Code
U0242
LAND ROVER
U — Network/User
Lost communication with headlight control module B
Views:
UK: 9
EN: 12
RU: 9
AI status
Completed
Completed
100%
Causes
- Faulty or missing power/ground to the headlamp control module B
- Damaged, corroded, or disconnected wiring or connectors (including CAN bus lines)
- Blown fuse or failed relay supplying the module
- CAN bus fault (open, short to battery/ground, improper termination)
- Failed headlamp control module B (internal electronics or firmware)
- Software or calibration mismatch after module replacement or update
Symptoms
- Driver information/warning lamp or message about headlamp/module communication
- Headlamp B inoperative, stuck, flickering, or not responding to controls
- Reduced or no automatic headlamp function for that side (if applicable)
- Related systems showing reduced functionality or additional communication DTCs
- Possible loss of CAN bus messages to other modules (intermittent)
What to check
- Connect a diagnostic scan tool; read and record U0242 and any related network DTCs
- Check vehicle battery voltage and charging system (stable 12–14.5 V during test)
- Visually inspect wiring, connectors, and grommets for damage, corrosion, or water ingress at the module and along harness
- Verify module power and ground with a multimeter at the module connector
- Check relevant fuses and relays for the headlamp/module circuit
- Measure CAN bus voltages and termination resistance (check CANH/CANL idle and dominant voltages and ~60 Ω across bus)
Signal parameters
- Vehicle battery: nominal 12–14.5 V with engine running
- CAN bus idle voltages: CANH ≈ 2.5 V, CANL ≈ 2.5 V (approx. equal); dominant state: CANH ≈ 3.5 V, CANL ≈ 1.5 V
- CAN bus differential (dominant) ≈ 2.0 V; termination resistance ≈ 60 Ω across CANH–CANL
- Module power pin ≈ battery voltage with ignition ON; ground pin ≈ 0 V
- Expected message frequency: periodic headlamp status messages typically repeat (varies by manufacturer) — absence indicates lost comms
Diagnostic algorithm
- Use a scan tool to confirm U0242 and note any additional U0xxx or B/C/P codes. Record freeze-frame and occurrence conditions.
- Verify battery voltage is within specification. Low voltage can cause network and module faults.
- Visually inspect the headlamp control module B and harness for damage, corrosion, moisture, or loose connectors. Repair or secure connectors as needed.
- Check and verify fuses/relays that feed the headlamp control module; replace if blown.
- With ignition ON, measure power and ground at the module connector. Repair any open or high-resistance circuits.
- Measure CANH and CANL at the module connector with a multimeter/scope. Confirm idle and dominant levels and check for ~60 Ω termination. If voltages are out of range, trace wiring toward the bus and inspect for shorts or opens.
- If bus voltages are normal, use a scope or capable scan tool to look for valid CAN frames from module B. If no frames, inspect module-side wiring and connector pins for continuity to the bus and other nodes.
- Perform wiggle and connector cleaning tests while monitoring the network for changes. Repair or replace damaged wiring/harness sections.
- If a single module is causing bus errors (bus-off), disconnect the module (if safe and recommended by manufacturer) to see if network returns to normal. Use caution with lamps that use high-voltage drivers; isolate power before disconnecting.
- If wiring, power, and bus appear good but the module does not communicate, consult manufacturer service information for reprogramming or module replacement. Replace the module only after verifying wiring and network integrity.
- Clear codes and perform a road/test verification of the system. Re-scan to confirm resolution.
Likely causes
- Loose/corroded connector at headlamp control module B
- Open or shorted CAN-H or CAN-L wiring near the module
- Blown module fuse or bad power feed
- Module has entered bus-off state due to repeated errors
- Module internal failure after water intrusion or impact
Fault status
Status
Lost communication with Headlamp Control Module B — module not responding on vehicle network (CAN).
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
Similar codes
HTML Workshop Manuals AI manual library for LAND ROVER Click to show available manuals 1
LAND ROVER 2015 Discovery Sport HSE
HTML ManualWorkshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email