B2602 – Left low beam circuit open (Hyundai)

B2602 means your Hyundai has an open circuit in the left low-beam headlamp circuit. For most drivers, the real-world effect is simple and serious. The left low beam may not work, or it may work only sometimes. According to Hyundai factory diagnostic data, this code indicates “Left low beam circuit open.” This is a Hyundai-defined body code, so the exact control path can vary by model and year. The code does not prove a bad bulb or a bad module. It tells you the control unit sees a break in the electrical path it expects.

B2602 Quick Answer

B2602 on Hyundai points to an open circuit in the left low-beam circuit. Start by verifying left low-beam operation, then load-test the power and ground at the left headlamp connector before replacing parts.

What Does B2602 Mean?

Official definition: “Left low beam circuit open.” In plain terms, a Hyundai body-related controller commanded or monitored the left low beam and did not see the electrical result it expected. In practice, the left low beam may be out, dim, or intermittent. This matters because an “open” usually comes from a wiring, connector, bulb, fuse, or ground path problem, not a logic failure.

What the module checks: Depending on Hyundai platform design, the controller may monitor circuit continuity, current flow, or voltage feedback on the left low-beam output. It may do this through a smart driver inside a module or through a relay-controlled feed. Why that matters: You must confirm whether the circuit lacks power, lacks ground, or loses continuity under load. The DTC points to the suspect trouble area, not the failed part.

Theory of Operation

Under normal operation, the driver selects low beams and the Hyundai lighting controller supplies power to the left low-beam bulb. Some vehicles route power through a fuse and relay. Others use an internal solid-state driver. The bulb returns current to ground through a chassis ground point or a dedicated ground wire.

B2602 sets when the controller commands the left low beam but sees an “open” condition. That happens when current cannot flow through the intended path. A broken filament can cause it, but so can a loose terminal, corrosion, a damaged harness near the headlamp, or a poor ground that opens under load. Some Hyundai modules also disable the output to protect the driver when they detect an open.

Symptoms

Drivers and technicians typically notice one or more of these symptoms with B2602:

• Left low beam inoperative when the headlamps switch to low-beam mode
• Intermittent operation that changes with bumps, rain, or engine vibration
• Dim left low beam if the circuit partially opens at a heated connector
• Headlamp warning on the cluster if the vehicle supports lamp-out indication
• High beams still work on the left side if they use a separate circuit
• One headlamp works while the right low beam operates normally
• DTC resets quickly after clearing when the module runs its lamp check

Common Causes

• Open power feed to the left low beam: A break in the B+ feed stops current flow, so the module sees an open when it commands the lamp on.
• Blown left low beam fuse or fusible link: An open fuse interrupts the circuit upstream, which makes the entire left low beam branch appear electrically dead.
• Corroded or overheated left headlamp connector: Heat and corrosion increase resistance until the terminal loses contact, which the module interprets as an open circuit.
• Broken ground path at the left headlamp: A loose ground bolt, corroded eyelet, or damaged ground wire prevents lamp current and mimics an open load.
• Damage in the front harness near the radiator support: Hyundai front harnesses often flex and rub in this area, which can break the low beam wiring internally.
• Faulty left low beam bulb or LED driver module: A failed filament, internal open, or failed driver removes the electrical load that the module expects to see.
• Failed headlamp relay or internal relay contact issue: Pitted or burnt relay contacts can open under load even when the relay clicks.
• BCM/IPM output driver fault or poor output pin fit: A failed driver or spread terminal at the module connector can prevent current delivery and set an open-circuit fault.

Diagnosis Steps

You need a capable scan tool with body/BCM access, a quality DVOM, and a test light that can load circuits. Use back-probes and terminal test adapters to avoid damage. Have basic hand tools for headlamp access. A wiring diagram for your Hyundai platform speeds pin identification and connector locations.

1. Confirm B2602 with a scan tool and record stored, pending, and history status. Save freeze frame data if the Hyundai module provides it. Focus on battery voltage, ignition state, headlamp switch request, and any lighting-related inputs at the time the code set.
2. Perform a quick visual inspection before meter work. Check the left low beam bulb, connector condition, and harness routing near the left headlamp and radiator support. Look for melted plastic, green corrosion, chafed tape, or prior repair splices.
3. Check fuses and power distribution for the left low beam circuit. Verify each related fuse feeds power on the correct side with ignition and lighting commanded as required. Do not stop at continuity checks, since a cracked fuse can pass continuity with no load.
4. Command the left low beam ON with the scan tool output test if available. If the scan tool cannot command outputs, use the headlamp switch. Note whether the right low beam works normally, since that comparison helps isolate shared inputs versus a left-side branch issue.
5. Verify the module’s power and ground integrity under load. Use voltage-drop testing, not just unloaded voltage. With the low beams commanded ON, measure ground drop at the BCM/IPM ground points and keep it under 0.1V drop while the circuit operates.
6. Check for voltage at the left low beam connector with the circuit commanded ON. If you see proper feed voltage, load the circuit with a test light to confirm the feed can deliver current. A weak feed often shows voltage on a meter but collapses under load.
7. Test the left low beam ground path with a voltage-drop test under load. Keep the lamp commanded ON and measure from the bulb ground terminal to battery negative. A drop over 0.1V points to high resistance in the ground wire, eyelet, splice, or body ground point.
8. If the connector lacks a solid feed, work upstream by sections. Check the relay output (if equipped), then the fuse output, then the module output pin. Back-probe and load-test each point to find where voltage stops or collapses.
9. Inspect and test connector fit and terminal tension at the headlamp connector and any intermediate connectors. Perform a pin-drag test where appropriate and look for spread terminals. Repair terminal issues before replacing any module or lamp assembly.
10. If freeze frame suggests an intermittent event, capture a scan tool snapshot during a wiggle test. Freeze frame shows conditions when B2602 set, while a snapshot helps you catch brief opens while flexing the harness. Focus on headlamp switch request, BCM output state, and system voltage during the event.
11. After repairs, clear DTCs and retest operation. Cycle the headlamps multiple times and road test if needed. A hard open monitored by the comprehensive component monitor often returns immediately at key-on when the fault remains.

Professional tip: Use a headlamp bulb or a high-current test light as a substitute load at the connector. A DVOM can show full battery voltage through a corroded strand. The substitute load forces current flow and exposes voltage drop. This approach prevents unnecessary BCM or headlamp assembly replacement.

Possible Fixes

• Repair the open in the left low beam feed or ground: Restore continuity and current capacity by repairing the damaged wire, splice, or terminal found during load testing.
• Clean and retension terminals at the headlamp connector: Remove corrosion, correct pin fit, and replace heat-damaged connectors to restore a stable electrical connection.
• Replace the failed bulb or LED driver only after circuit tests pass: Install the correct Hyundai-spec bulb or serviceable driver once you confirm proper power and ground at the connector.
• Replace a verified faulty relay or fuse element: Replace the component only when testing proves it opens under load or fails to pass current.
• Restore power/ground integrity at the BCM/IPM connection points: Repair loose grounds, damaged module connector terminals, or poor pin fit that prevents the module from delivering output current.

Can I Still Drive With B2602?

You can usually drive with B2602, but you should treat it as a lighting safety fault. On Hyundai vehicles, this code points to an open circuit in the left low beam circuit. That often means the left low beam will not light. Daytime driving may seem normal, but night driving becomes risky fast. Rain, fog, and tunnels also raise the hazard. If the right low beam still works, you may limp the vehicle to a safe place or a repair shop. Avoid high-speed night driving. Do not rely on high beams as a “fix.” A working high beam does not replace a low beam pattern and can blind other drivers. If both low beams act up, stop and repair immediately.

How Serious Is This Code?

B2602 ranges from an inconvenience to a real safety issue. When only the left low beam fails, the car still runs normally. No drivability damage occurs. The serious part involves visibility and legality. Many areas treat a low beam outage as an equipment violation. Reduced forward lighting and poor road-edge illumination increase crash risk. The problem becomes urgent if the vehicle uses the low beam circuit for other body functions on your Hyundai platform. Some models route headlamp control through a body module and a relay network. A harness fault can then create intermittent flicker, heat at the connector, or repeated fuse stress. Treat any melting odor, hot connector, or repeated fuse failure as an immediate stop-and-repair condition.

Common Misdiagnoses

Technicians often replace the left headlamp bulb or LED assembly first and stop there. That wastes money when the circuit actually opened at the connector, ground, fuse output, or in the harness near the radiator support. Another common error involves skipping load testing. A corroded terminal can pass a meter’s no-load voltage check yet fail under lamp load. Shops also misread the code as a “bad module” and condemn the body controller early. On Hyundai lighting circuits, confirm power and ground at the lamp connector with the circuit loaded before any module call. Also inspect prior collision repairs and aftermarket HID/LED conversions. Those frequently introduce open circuits and poor pin fitment.

Most Likely Fix

The most frequently confirmed repair direction involves restoring continuity at the left low beam lamp connector or its nearby harness. Look for spread terminals, corrosion, water entry, or a partially backed-out pin. The next most common fix repairs an open in the power feed or ground leg between the lamp and the Hyundai body/lighting control path. Verify the fix by commanding low beams on, checking stable voltage and ground voltage-drop under load, and then road-testing at night conditions. Drive long enough to reproduce the original failure pattern, since enable criteria and self-check timing vary by Hyundai platform.

Repair Costs

Repair cost depends on whether the confirmed root cause is a sensor, wiring, connector issue, or control module problem. Verify the fault electrically before replacing parts.

Last updated: March 31, 2026