B1519 — Hood Switch Circuit Failure

Does B1519 always mean the hood is actually open?

No. B1519 can remain set when the hood is closed if the switch, connector, wiring, or latch adjustment has failed, so the circuit should still be tested.

Can I drive with OBD2 code B1519 stored?

Driving may be possible if the hood is securely latched and no hood warning is present, but the unreliable status input should be diagnosed promptly.

Will an ELM327 scanner diagnose B1519?

An ELM327 scanner can confirm the code and monitor hood-switch data, but physical inspection and wiring or switch testing are still required to locate the fault.

What is the most common repair for B1519?

Common repairs include adjusting or replacing the hood switch, cleaning a corroded connector, or repairing damaged wiring near the latch before clearing the code.

When your vehicle's diagnostic system detects a problem with the hood switch circuit, it stores trouble code B1519. This code falls under the body electrical category and specifically indicates that the body control module is receiving unexpected readings from the hood position sensor or its associated wiring. The BCM expects a specific voltage signal when the hood is open or closed, and B1519 triggers when that signal stays outside the normal operating range.

The body control module continuously monitors the hood switch as part of its supervisory role over the vehicle's security and convenience systems. On most vehicles, this input affects functions like the alarm system, interior lighting when entering or leaving the vehicle, and sometimes the automatic locking feature. When the module sees erratic, absent, or incorrect voltage from this circuit across multiple drive cycles, it flags B1519 and illuminates the check engine or body warning light. The stored freeze frame data captures engine RPM, load, temperature, and vehicle speed at the exact moment the fault occurred, giving you a reliable starting point for troubleshooting.

Setting B1519 does not mean the engine or drivetrain has a problem. Instead, it signals a fault within the body electronics that may affect how your car locks, lights up when you approach, or protects itself with the security system. Understanding this distinction helps you prioritize your diagnostic steps without chasing unrelated issues.

Symptoms

• The hood ajar indicator stays illuminated on the dashboard even when the hood is fully closed
• Security alarm may arm or disarm inconsistently or fail to operate correctly
• Interior lights may not turn on when the hood is opened, or may stay on when it should be closed
• Central locking may behave erratically or disable certain automated functions
• Other body electrical functions such as power windows or wipers operate intermittently or stop responding
• The check engine or body system warning light remains on after the fault is detected
• No noticeable change to engine performance, fuel economy, or throttle response in most cases

Causes

• Corrosion or moisture intrusion at the hood switch connector, especially in vehicles exposed to rain or car washes
• Loose or unplugged electrical connector at the hood switch or hood release mechanism
• Broken, chafed, or pinched wiring harness near the hood hinge or fender, where repeated flexing damages conductors
• Blown fuse protecting the hood switch circuit or associated body control module circuits
• Failed hood switch or bonnet switch itself, with internal contacts wearing out over time
• Faulty body control module unable to process the switch signal correctly
• Damaged relay that supplies power to the hood switch circuit

How to Diagnose

1. Connect an OBD2 scanner compatible with body codes, retrieve B1519, and record all freeze frame information. Note the engine speed, load percentage, coolant temperature, and vehicle speed recorded when the fault first appeared.
2. Check for any accompanying trouble codes in the body control module. Related codes such as sensor reference voltage faults or communication errors often point to the true root cause. Research any published TSBs for your specific make and model that address B1519, as manufacturers sometimes release software updates or service campaigns for recurring issues.
3. Perform a thorough visual inspection of the wiring harness running to the hood switch. Focus on areas near hinges, hood release mechanisms, and the fender well where wires experience repeated bending. Look for cracked insulation, green corrosion buildup, or connectors that are not fully seated.
4. Test the hood switch circuit with a multimeter. With the hood closed, you should see a specific reference voltage or ground signal depending on your vehicle's circuit design. Operate the switch manually while monitoring live data on your scanner if the system supports it.
5. Verify fuse and relay condition in the appropriate junction boxes. Replace any blown fuses with the correct amperage rating and test related relays with a known-good substitute.
6. Clear B1519 after inspecting and testing, then complete a drive cycle that reproduces the conditions from the freeze frame data. If the code returns, the fault is confirmed and present during normal operation.

Repair Options

• Clean or reseat the hood switch connector, repair damaged wiring, or splice in new conductor sections: parts typically run $20 to $60, with labor adding $60 to $190 depending on accessibility
• Replace a failed hood switch or bonnet sensor assembly: part costs between $40 and $180, plus $80 to $270 in labor for most vehicles
• BCM diagnosis, repair, or full replacement: BCM repair may cost $150 to $400, while complete replacement including programming can reach $300 to $900 depending on the vehicle

How Much Does It Cost to Fix B1519?

The total repair bill for B1519 varies significantly depending on which component is responsible. Wiring repairs and connector fixes tend to fall at the lower end, typically between $80 and $250 when done at an independent shop. Switch replacement occupies the middle ground, generally costing $120 to $450 depending on the part price and labor time. The body control module route represents the most expensive scenario, ranging from $300 to $900 when diagnosis confirms a failed BCM requiring replacement and reprogramming. Most vehicles experiencing B1519 can be repaired for under $300, making an accurate diagnosis before purchasing parts the smartest first step.

Driving-Safety Verdict

B1519 carries a short-term severity rating. While this fault does not impair engine operation, it can compromise the security system, exterior lighting coordination, or central locking depending on your vehicle's programming. In most cases, you can continue driving without immediate concern, but having the fault diagnosed and repaired promptly is advisable to restore full alarm function and prevent being stranded by a dead battery if a stuck circuit drains power overnight.

Related OBD2 codes

• B1500: Lamp Turn Signal Left Circuit Open
• B1501: Lamp Turn Signal Left Circuit Short To Battery
• B1502: Lamp Turn Signal Left Circuit Short To Ground
• B1503: Lamp Turn Signal Right Circuit Failure
• B1504: Lamp Turn Signal Right Circuit Open
• B1505: Lamp Turn Signal Right Circuit Short To Battery