B16A2 – Left turn signal bulb outage (Mitsubishi)

Mitsubishi-specific code — factory diagnostic data

Last updated: March 29, 2026

Definition source: Mitsubishi factory description · Autel MaxiSys Ultra & EV. Diagnostic guidance is based on factory-defined fault logic for this code.

B16A2 means the left turn signal lamp is not working the way your 2016 Mitsubishi Outlander expects. You will usually notice a dead left blinker, a fast “hyper-flash,” or a dash message. According to Mitsubishi factory diagnostic data, this code indicates a left turn signal bulb outage. This is a Body system DTC, so it points to the exterior lighting circuit and the module that monitors lamp load. The code does not prove a bad bulb. It tells you the vehicle saw an abnormal electrical load or feedback while commanding the left turn signal on.

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B16A2 Quick Answer

B16A2 on Mitsubishi means the Body system detected an outage condition on the left turn signal bulb circuit. Confirm the bulb operation and circuit load first, then verify power, ground, and connector integrity at the left turn lamp.

What Does B16A2 Mean?

Official definition: “Left turn signal bulb outage.” In plain terms, the vehicle believes the left turn signal lamp did not light correctly when commanded on. In practice, this can show up as a left turn signal that does not illuminate, flashes rapidly, or works intermittently.

What the module is actually checking: the Mitsubishi body-side lighting control logic monitors the left turn output for a “normal” electrical signature while it drives the lamp. Depending on platform design, it may infer bulb status from output current draw, voltage drop on the driver circuit, or feedback from the lamp circuit. Why that matters: an “outage” result can come from an open bulb filament, high resistance in a socket, poor ground, damaged wiring, or a fault in the driver stage. You must verify the circuit under load before you replace parts.

Theory of Operation

Under normal operation, the body electrical system commands the left turn signal on and off at a fixed rate. Power flows through the turn signal feed and the bulb filament, then returns to ground. The module expects a stable load and a predictable voltage drop when the lamp turns on.

When the bulb opens, the socket loses contact, or resistance climbs in the ground path, the load signature changes. The module then flags an outage because it cannot confirm normal lamp current or feedback. Some Mitsubishi strategies also change the flash rate to alert the driver. That flash change supports diagnosis, but it does not identify the root cause.

Symptoms

You will usually notice a turn-signal behavior change first, then the code follows in memory.

• Hyper-flash left turn indicator flashes faster than normal
• No left signal left front or left rear turn lamp does not illuminate
• Intermittent operation left turn lamp works sometimes, then cuts out over bumps
• Dim lamp left turn lamp lights but looks weak compared to the right side
• Cluster indicator left arrow on the dash flashes rapidly or behaves unevenly
• Warning message exterior lamp warning appears, if equipped
• Hazard behavior hazards show a dead or erratic left-side flash

Common Causes

• Failed left turn signal bulb filament: An open filament drops current flow, so the body controller flags a bulb outage.
• Incorrect bulb type or wattage installed: The wrong load changes circuit current, and Mitsubishi bulb-out logic can interpret it as an outage.
• Poor bulb socket contact tension: Loose terminals create intermittent contact, which makes the lamp drop out during vibration or heat soak.
• Corrosion or moisture in the socket: Oxidation increases resistance and reduces lamp current until the module decides the bulb looks “out.”
• Open or high-resistance feed wire to the left turn lamp: A damaged wire or splice limits current to the bulb and mimics a burned-out lamp.
• High-resistance ground at the left lamp assembly: A weak ground raises voltage drop under load and makes the bulb dim or inoperative.
• Connector pin fit issue at lamp or body harness: Spread terminals or poor pin retention creates intermittent opens that set the code during signaling.
• Aftermarket LED conversion without proper load control: Low LED current can trigger an outage decision unless the circuit uses approved load management.
• Short-to-ground or short-to-power affecting the lamp circuit: A short can force the module to disable the output or detect an implausible current condition.
• Body control module output driver fault (less common): An internal driver that cannot source or switch current correctly can look like a persistent bulb outage after wiring checks.

Diagnosis Steps

Use a scan tool that can access Mitsubishi body codes and live data. Have a DVOM, a test light, and back-probing tools. A wiring diagram and connector views matter on the 2016 Outlander. Use voltage-drop testing under load, not continuity alone. If the fault acts intermittent, use a scan-tool snapshot while you operate the turn signal.

1. Confirm DTC B16A2 and record freeze frame data. Focus on battery voltage, ignition state, and any lamp/turn-signal status PIDs available. Freeze frame shows conditions when the DTC set. A snapshot captures the moment an intermittent drop-out happens during your test.
2. Check power distribution first. Inspect related fuses for turn/hazard/ETACS or body power feeds. Also do a quick visual inspection of the left turn lamp, lens, socket, and harness routing before you touch the module.
3. Verify the module’s power and ground integrity under load. Perform voltage-drop tests with the circuit operating. Target less than 0.1V drop on grounds while the left turn signal flashes. High resistance can pass continuity checks and still fail under load.
4. Operate the left turn signal and hazards. Watch the lamp for dimming, fast flash, or intermittent operation. Compare left versus right brightness and flash cadence. Note whether the issue changes with hazards, since that can change the commanded output strategy.
5. Use the scan tool to review body/ETACS data and outputs. Check any available “turn signal output command” and “bulb outage” or “lamp current” status. Verify whether the module commands the left output ON while the lamp stays OFF.
6. Inspect the left turn bulb and socket carefully. Confirm the bulb type matches Mitsubishi specifications for that lamp position. Look for a distorted base, heat damage, or a broken filament. If the vehicle uses an LED assembly, inspect for signs of water intrusion or internal failure.
7. Check the socket and connector pin fit. Look for corrosion, spread terminals, or loose pin retention. Perform a wiggle test while the signal operates. If the lamp flickers, isolate the movement point and inspect that segment closely.
8. Load-test the feed side of the circuit. With the turn signal commanded ON, measure voltage at the bulb socket feed. If voltage looks normal unloaded, apply a test light load in place of the bulb to prove the circuit can carry current. A weak feed will drop voltage under load.
9. Voltage-drop test the ground path at the lamp. Keep the bulb installed and flashing. Measure between the bulb ground terminal and the battery negative post. If drop exceeds 0.1V, repair the ground connection, terminal, or ground point.
10. Check for shorts if the fuse blows, the output shuts down, or the reading looks unstable. Inspect the harness where it passes through body seams and near the lamp pocket. Look for rubbed insulation and aftermarket splices. Repair wiring faults, then retest.
11. After repairs, clear the DTC and run a functional verification. Cycle left turn and hazards for several minutes. Road-test on a rough surface if the fault acted intermittent. Recheck for pending versus stored codes, since some body faults return immediately on key-on if the issue remains.

Professional tip: Don’t trust a quick continuity check on the lamp ground. Corrosion often leaves continuity intact. The circuit fails only when current flows. Voltage-drop under load exposes that problem fast. If B16A2 returns immediately after clearing, treat it like a hard fault and stay focused on feed, ground, and terminal tension at the lamp.

Possible Fixes

• Replace the left turn signal bulb with the correct type: Install the specified bulb and confirm normal flash rate and brightness.
• Clean and restore socket terminal contact: Remove corrosion, repair heat damage, and correct terminal tension to restore reliable current flow.
• Repair wiring, splices, or connector pin fit: Fix opens or high resistance in the feed or ground path, then secure the harness to prevent repeat damage.
• Service the left lamp ground point: Clean the ground connection and verify less than 0.1V drop under load with the lamp flashing.
• Correct aftermarket LED or accessory wiring issues: Remove improper LED conversions or add proper load management only after verifying Mitsubishi circuit design.
• Replace the lamp assembly or module only after circuit proof: If feed and ground test good under load and the output logic still fails, follow Mitsubishi pinpoint tests before replacing an assembly or body control module.

Can I Still Drive With B16A2?

You can usually drive a 2016 Mitsubishi Outlander with B16A2, but you should treat it as a safety-related fault. This manufacturer-specific Mitsubishi code points to a suspected left turn signal bulb outage. Other drivers may not see your intent to turn. That raises crash risk, especially at night or in heavy traffic. Use hand signals if needed and avoid lane changes. If the left front or left rear turn signal stays dark, fix it before regular driving. If the hazard lamps also act abnormal, stop and diagnose sooner. A multi-function lighting issue can remove other exterior lighting functions.

How Serious Is This Code?

B16A2 ranges from an inconvenience to a real safety concern. It becomes mostly an inconvenience when only the cluster indicator flashes fast but the exterior lamps still flash correctly. It becomes a safety issue when the left turn signal lamp does not illuminate, flashes intermittently, or causes other lamps to backfeed or flicker. The Outlander’s body lighting control logic can flag an outage when it sees abnormal current draw or an implausible feedback signal. That logic can also react to corrosion or a poor ground. The vehicle will still run and drive normally. Your ability to signal safely may not.

Common Misdiagnoses

Technicians often replace the left turn bulb immediately and stop testing. That wastes time when the real problem sits in the socket, ground, or connector. A common miss involves LED retrofits. They change current draw and can trigger outage logic on Mitsubishi body systems. Another frequent error comes from checking voltage with the lamp removed. That looks “good” but proves nothing under load. Always load-test the circuit and check voltage drop on the ground side while the lamp commands on. Also avoid blaming the BCM without proving output control, connector tension, and water intrusion at the lamp housing.

Most Likely Fix

The most common confirmed repair direction for B16A2 involves restoring proper current flow at the left turn signal lamp. Start with circuit verification, not parts. Many Outlanders set this code due to a failed filament bulb, a heat-damaged socket, or corrosion in the lamp connector that increases resistance. After you clean and repair the connector or replace the bulb with the correct type, verify operation with the lamp installed and flashing. Then clear the code and recheck after several left-turn commands. Enable criteria vary by Mitsubishi platform, so confirm with service information if the code needs multiple cycles to rerun.

Repair Costs

Repair cost depends on whether the confirmed root cause is wiring, connector condition, a sensor, a module, or the labor needed to diagnose the fault correctly.