Modern vehicles have more than 60 possible dashboard warning lights. Most drivers recognize only a handful of them — and when an unfamiliar symbol appears, the instinct is often to ignore it and hope it goes away. That instinct has caused thousands of preventable breakdowns and engine failures. Here is what the most important warning lights actually mean.
Red warning lights — stop driving or act immediately
🔴 Oil pressure warning (oil can icon)
This is the most critical warning light on any vehicle. It means oil pressure has dropped to a level where engine bearings and camshafts are receiving inadequate lubrication. Metal-on-metal contact begins immediately. Pull over and turn off the engine within seconds — not minutes. Check the oil level before restarting. Related codes: P0520, P0521, P0522.
🔴 Engine temperature warning (thermometer icon)
The engine has exceeded its maximum safe operating temperature. Pull over immediately and turn off the engine. Do not remove the radiator cap while hot. Common causes: coolant leak, failed thermostat, broken water pump, clogged radiator. Related code: P0217.
🔴 Battery / charging warning (battery icon)
The charging system is not maintaining battery voltage. The alternator may have failed. The vehicle will run on battery power alone — typically 20–45 minutes before electrical systems begin failing. Drive directly to a shop. Related codes: P0562, P0620.
🔴 Brake warning light
If the handbrake is not applied, a red brake warning light means low brake fluid level — potentially indicating a brake fluid leak or severely worn brake pads. Do not drive with reduced braking ability. Have it inspected immediately.
🔴 Airbag / SRS warning (person with circle icon)
The supplemental restraint system has detected a fault. Airbags may not deploy in a crash. Related codes: B0001, B0002.
Amber/yellow warning lights — schedule service soon
🟡 Check engine light (engine outline icon)
Steady amber: a fault has been stored. Safe to drive but schedule a diagnostic soon. Flashing: active misfire — pull over immediately. See the full guide: What does the check engine light mean?
🟡 TPMS (tire pressure) warning
One or more tires are significantly underinflated (typically more than 25% below the recommended pressure), or a TPMS sensor has failed. Check tire pressure immediately — underinflated tires affect handling and can fail at highway speeds. Related codes: C0750–C0765.
🟡 ABS warning light
The anti-lock braking system has detected a fault. Normal braking still works, but ABS will not activate during hard stops. Do not drive aggressively — increase following distance. Related codes: C0035, U0121.
🟡 Traction control / stability control (car with skid lines icon)
If illuminated steadily (not flashing), it means traction or stability control has been disabled — either manually or due to a fault. A fault in a wheel speed sensor disables both systems. Related codes: C0040, C0045.
🟡 Transmission temperature warning
Transmission fluid is overheating. Pull over and let the transmission cool before continuing. Continued driving causes rapid fluid degradation and potential transmission failure. Related code: P0218.
🟡 Service engine soon
On some vehicles this is identical to the check engine light. On others it specifically means a scheduled service is due (oil change, spark plugs, etc.). Check your owner's manual to confirm which applies to your vehicle.
Blue and green indicator lights
- Blue temperature indicator — engine is still warming up. Normal — disappears after a few minutes of driving. Do not rev the engine hard until it goes off.
- Green lane departure / driver assist icons — driver assistance systems are active. Not a fault.
The one rule that applies to every warning light
Never ignore any warning light for more than a day or two without at least reading the associated code. A warning that seems minor today can become expensive quickly. Use the MyOBDCode dashboard light guide to look up any unfamiliar symbol on your vehicle.