Ensuring Your Vehicle’s Warning Lights Are Working

Turn the ignition to the ON position without starting the engine and confirm that key dashboard warning lights briefly illuminate, then start the engine and ensure they go out; if a light fails to come on during this check or stays on afterward, investigate or seek service. This quick routine—often called a “bulb check”—is the most reliable way to verify that your car’s alert system is functioning before you drive.

Why This Matters—and What “Working” Looks Like

Warning lights are your car’s early-warning system for issues ranging from low oil pressure to compromised braking and charging systems. On most vehicles, critical icons illuminate momentarily when you switch the ignition on, proving the lamp or display is capable of lighting. After the engine starts, healthy systems will extinguish their warnings. Some vehicles with digital clusters show a subset of icons or a consolidated self-test; always compare what you see to your owner’s manual.

A Step-by-Step Check You Can Do in Under a Minute

The following simple routine verifies that your dashboard warning lights and key exterior signals are doing their job before you set off.

1. Park safely and prepare: Put the transmission in Park (or Neutral for manuals), set the parking brake, and ensure good visibility of the instrument cluster.
2. Ignition on, engine off: Turn the key to ON (or press Start without pressing the brake/clutch). Watch the cluster for a brief illumination of critical icons—this is the system self-test.
3. Start the engine: Most warning lights should go out within a few seconds. Seat belt, parking brake, and some diesel preheat lights may remain until you buckle or release/complete their function.
4. Confirm exterior alerts: Activate hazard lights and walk around to verify all four indicators flash. If possible, press the brake pedal and use a reflection (garage door/window) or a helper to confirm all brake lights illuminate.
5. Address anomalies immediately: If a light doesn’t illuminate during the self-test, the circuit or icon may be faulty. If it stays on after startup, the system is reporting an active fault.

Done consistently, this checklist catches both burned-out indicators and emerging mechanical or electrical issues, reducing the risk of being caught off-guard on the road.

Which Dashboard Icons Should You Typically See?

While exact displays vary, most modern vehicles will briefly show several critical warnings at ignition-on. Here are the common ones and what their behavior means.

• Engine/Malfunction Indicator (Check Engine): Should illuminate at ignition-on and go out after start; staying on indicates an emissions or engine management fault.
• Oil Pressure: Should illuminate at ignition-on and extinguish within seconds after start; if it remains on, stop the engine immediately and check oil level/seek assistance.
• Battery/Charging System: Should illuminate at ignition-on and go out after start; remaining on suggests alternator or 12V system charging fault (applies to EVs/HEVs as well).
• Brake System/Red Brake: May illuminate with the parking brake engaged; should go out when released. If it stays on, check brake fluid level or for system faults.
• ABS: Should briefly illuminate and then go out; if it stays on, basic braking remains but anti-lock function is disabled—service soon.
• Airbag/SRS: Should illuminate briefly and then extinguish; remaining on indicates a restraint system fault that can affect airbag deployment.
• ESC/ESP/Traction: Often illuminates on self-test and then goes out; flashing while driving indicates active traction intervention, staying on indicates a stability control fault.
• TPMS (if equipped): Bulb check on ignition; staying on indicates low tire pressure or a sensor issue—check pressures with a gauge.
• Glow Plug/Preheat (diesel): Illuminates on ignition and goes out when preheating is complete; start after it goes out.
• Power Steering (EPS): Brief self-test; staying on indicates reduced or lost assist.

If your car does not display all of the above during self-test, it may be designed to show fewer icons or only when faults occur; consult the owner’s manual for model-specific behavior.

Verifying Exterior Warning and Signal Lights

Dashboard icons aren’t the only alerts that matter—your hazard lights, indicators, and brake lights are critical for signaling other road users. Here’s how to confirm they work.

1. Hazard lights: Press the hazard switch; walk around to confirm all four indicators flash (front, rear, and side repeaters where fitted).
2. Turn indicators: Test left, then right. Verify the dash arrow flashes at a normal rate; a rapid flash often indicates a failed bulb/LED.
3. Brake lights: With the ignition on, press the brake pedal and check reflections or ask a helper to confirm both rear lamps and the high-mounted stop lamp illuminate.
4. Tail, head, and reverse lamps (optional but recommended): Switch lights on and verify tails/front markers; engage reverse (with foot on brake) to confirm the reverse lamp, ensuring it’s safe to do so.

These checks improve your visibility to others and can alert you to a failed bulb, fuse, wiring fault, or LED module before it becomes a safety or legal issue.

Troubleshooting: If Lights Don’t Come On—or Won’t Go Out

If the self-test doesn’t appear or a warning persists, use the steps below to narrow down the cause and decide next actions.

• Cluster dimmer and daylight: Ensure the instrument panel dimmer isn’t set too low; bright sunlight can wash out icons.
• Owner’s manual behavior: Some vehicles don’t illuminate every icon at startup; confirm expected behavior for your model/year.
• Fuses and connections: Check the fuse for the instrument cluster and the specific light circuit; inspect connectors if accessible.
• Bulb/LED failure: Older clusters use bulbs that can burn out; newer LED clusters can fail at module or pixel level—requires professional repair.
• Software updates: Infotainment/cluster firmware updates from the manufacturer can resolve display glitches—ask your dealer.
• Persistent warnings:
  – Oil pressure or high temperature: Stop safely and shut down; check levels and call for assistance if uncertain.
  – Charging system: Minimize electrical load and head to a workshop; battery may discharge quickly.
  – ABS/ESC: Drive cautiously; braking works but without ABS/stability aids—service soon.
  – Airbag/SRS: Avoid tampering with seat or wiring; have the system scanned and repaired promptly.
  – TPMS: Check tire pressures with a gauge; top up and recalibrate if required, or service faulty sensors.
• Diagnostic scan: An OBD-II scan (many parts stores and mobile apps can help) retrieves fault codes that guide repairs.

Resolving the root cause quickly preserves safety systems and can prevent secondary damage, such as overheating or battery failure.

Good Habits to Keep Your Warning System Reliable

Simple routines and documentation make it easier to spot issues early and demonstrate proper maintenance if needed.

• Weekly startup check: Make the ignition-on self-test and a quick light walkaround a regular habit.
• After service or repairs: Verify that no new warnings appear and that all icons behave normally—report anomalies immediately.
• Keep spares where legal: For vehicles with replaceable bulbs, carry common spares and know how to fit them safely.
• Mind modifications: Aftermarket electronics or trailer wiring can affect warning systems; use quality harnesses and proper coding.
• Commercial vehicles and motorcycles: Follow pre-trip inspection protocols; two-person checks are often fastest and most reliable.

Consistent checks, plus accurate records in your maintenance log, help ensure your vehicle’s alerts remain trustworthy and legally compliant.

Safety and Legal Notes

Never ignore a red warning light—treat it as urgent. Amber warnings indicate caution and the need for timely attention. In many regions, driving with inoperative exterior lights or active critical warnings can result in fines or test failures, and it increases crash risk. When in doubt, stop safely and consult a professional.

Summary

To make sure warning lights are working, perform the ignition-on self-test, start the engine to confirm warnings clear, and verify exterior hazards, indicators, and brake lights. Investigate any icon that fails to appear during the self-test or stays illuminated afterward, using your manual, basic checks, and diagnostics as needed. Regular, brief checks keep your safety systems reliable and help you address problems before they escalate.

How to check if warning lights are working?

In order to check the accuracy of the warning light bulbs themselves, each time the car is switched on the warning lights will appear for several seconds and then go off. This allows the motorist to do a quick visual check to ensure all the warning lights are working properly.

How can you make sure warning lights are working?

To check if warning lights are working, turn the ignition to the ‘On’ position and observe if the lights illuminate briefly. Ensure you identify which lights should turn on, check for blinking signals, and refer to the vehicle manual for guidance.

Can I diagnose my dashboard lights myself?

And make sure everything’s well lit you should be able to see the full spectrum of the speedometer. Or the tachometer. And the speedometer. And your warning gauges.

How do I reset my dashboard warning lights?

To reset a dashboard warning light, the most effective method is to first identify and fix the underlying problem, then use a diagnostic tool to clear the code and reset the light. For minor issues or temporary glitches, you can try a hard reset by disconnecting the negative battery terminal for about 15 minutes, or by following specific procedures outlined in your vehicle’s owner’s manual, such as cycling the ignition key or pressing dashboard buttons. 
1. Address the Underlying Issue

• Identify the warning: Determine which light is on and what it signifies, as each light indicates a different potential problem. 
• Fix the problem: Before resetting the light, ensure the actual issue is repaired. For example, if it’s a low oil pressure light, add oil; if it’s a check engine light, have the engine diagnosed and repaired. 

2. Use a Diagnostic Tool 

• Plug in the OBD-II scanner: Connect the scanner to your car’s OBD-II port, typically found under the dashboard. 
• Read and clear codes: Follow the prompts on the scanner to read the error codes and then clear them. 

This video demonstrates how to use an OBD-II scanner to diagnose and reset dashboard warning lights: 58sDiagnostic WorldYouTube · Apr 14, 2020
3. Perform a Manual Reset
If you don’t have an OBD-II scanner or the issue was a temporary glitch, you can try manual reset methods. 

• Disconnect the battery: Opens in new tabTurn off the ignition and disconnect the negative battery terminal for 15-20 minutes, then reconnect it. 
• Cycle the ignition: Opens in new tabTurn the key to the “On” position (without starting the engine) and leave it there for several minutes. 
• Use vehicle-specific procedures: Opens in new tabConsult your owner’s manual for any specific instructions for your car’s make and model, as some vehicles have unique reset sequences. 

Important Considerations

• Safety: Do not ignore warning lights that return after a reset, as they may indicate a serious fault that requires professional attention. 
• Professional help: If at-home methods fail, a certified mechanic can diagnose and reset warning lights with specialized equipment.