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Dash Warning Lights


Check engine Also called the "Malfunction Indicator Lamp" or (MIL), an illuminated CHECK ENGINE LIGHT means you vehicle has detected a potential emissions fault. The computer has logged one or more diagnostic trouble codes that correspond to the problem and turned on the warning lamp to alert you to the problem.

There is NO WAY to determine the nature of the problem without connecting a scan tool to the vehicle's diagnostic connector to read the fault code(s). Once this has been done, further diagnosis and testing may be required to isolate the fault so the correct parts(s) can be replaced.

Don't be alarmed by a CHECK ENGINE light. Often the problem is something minor that will NOT affect the way your engine runs, or you car's ability to start or drive. Depending on the nature of the fault, your engine may not run as good as it normally does, or it may use more fuel than usual. But usually the problem does NOT require immediate attention. You can continue to drive your car until it can be diagnosed.

Common reasons for the CHECK ENGINE light to come on include a loose gas cap, fouled spark plugs, dirty fuel injectors, the failure of an engine sensor such as the oxygen sensor, throttle position sensor or manifold absolute pressure sensor, or a problem in an emissions control system or device such as the EGR valve or catalytic converter.

The oil pressure warning light comes on when oil pressure drops below a minimum threshold (the exact pressure will vary from one vehicle to another). No engine will run very long if it runs out of oil. The bearings will run dry, overheat and seize, causing severe engine damage (spun bearings, damaged crankshaft journals, broken connecting rods, etc.).

The underlying cause of a low oil pressure warning light is usually a low oil level in the engine's crankcase. This, in turn, may be due to leaky gaskets or seals, or worn valve guides, piston rings and/or cylinders that are causing the engine to burn oil. Leaky gaskets and seals are usually not too expensive to replace (except for the rear main crankshaft seal which is difficult and expensive to replace). The only fix for a worn engine that is burning oil is to overhaul or replace the engine (very expensive!)

Other causes of an low oil pressure warning light include a worn oil pump or a faulty oil pressure sending unit.

The temperature warning lamp is on because your engine overheated. Continuing to drive can cause expensive engine damage (head gasket failure, cracks in the cylinder head, piston scuffing, valve stem galling, etc.)

Your engine may have overheated for a variety of reasons. The most common cause is a low coolant level (check the radiator, hoses and engine for coolant leaks). Other common causes include a stuck thermostat, a cooling fan that is not working, a failed water pump, obstructions that block airflow through the radiator (bugs, debris, plastic bags), a buildup of scale or sludge inside your cooling system, or overworking your engine or air conditioning system during unusually hot weather. Towing a heavy trailer or prolonged mountain driving may also cause your engine to run hotter than normal.

If the coolant level is low, add coolant after the engine has cooled off. Check for leaks. If you see none, start the engine and cautiously proceed. If the engine starts to overheat again, your engine may have an internal coolant leak (Bad news because it means a leaky head gasket or cracks in the cylinder head or block), or there is some other problem (bad thermostat, water pump, etc.).

If you see a coolant leak, you may be able to temporarily stop the leak by adding a can of cooling system sealer to the radiator. This may temporarily plug the leak or slow it down enough so you can continue driving until the leak can be fixed.

This warning light comes on when the charging system is NOT producing enough current or voltage to meet your vehicle's electrical needs. The cause may be a failed alternator or generator, a failed voltage regulator (if separate from the alternator), loose or corroded battery cables, or a broken or slipping drive belt. Turn the engine off and check the belt that turns the alternator. Caution: DO NOT get your fingers, clothing or tools near the belt(s) or pulleys while the engine is running. If the belt appears to be intact and is turning the alternator, start the engine, and turn on the headlights. If the lights are dim, it verifies the charging system is not working -- probably due to a failed alternator or other electrical fault.

First, check the parking brake lever, handle or pedal. Make sure it is fully released. If that is not the problem, test the brakes by pressing on the brake pedal. If the light comes on only while pressing the pedal, it means one of the hydraulic circuits in the brake system has lost pressure -- probably because of a leak (bad brake hose, leaky disc brake caliper or drum brake wheel cylinder). Your vehicle may or not be able to stop with this kind of problem, making it unsafe to drive. If the pedal feels unusually low or goes to the floor, DO NOT attempt to drive the vehicle. Have it towed to a service facility for repairs (or fix it yourself).

If the Brake Warning light remains on all the time, the problem may be a low fluid level in the master brake cylinder reservoir. Many vehicles have a fluid level sensor that comes on if the fluid level gets low. This may also occur when braking hard or braking on an incline because of the fluid sloshing inside the reservoir. Check the brake fluid level and add fluid as needed if low. The brake system should also be inspected for leaks or worn linings.

Check all the lights on your vehicle when it is safe to do so (not in the middle of the highway at night!), and replace any bulbs that have burned out. In some cases, the problem might be a corroded or loose socket, loose or corroded wiring, or a blown fuse.


Warning light airbag A warning light that looks like this or says SRS should NEVER come on unless there is a fault in your vehicle's air bag system (supplemental restraint system or SRS). Like the engine computer and ABS computer, the air bag control module runs a self-check every time the vehicle is driven. If it finds a fault in a crash sensor, one of the air bag modules, the wiring or itself, it will set a code, turn on the warning light and disable itself. You can drive the vehicle but the air bag(s) will NOT deploy should you be involved in an accident. You should have the problem diagnosed and repaired at your earliest convenience.

Many service reminder lights have a RESET button that allows you to turn off the light and reset the interval period. On some, though, a scan tool is required to turn off and reset the light.


Many vehicles have their own unique warning lights or icons to alert you when something is wrong. You can usually find these in the back of your vehicle owners manual. Note: The appearance of some warning lights will vary depending on the country where the vehicle is sold. Below are some typical warning lights for a late model Lexus (courtesy Toyota):

Click to see larger image.


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