Dashboard warning and malfunction indicator lights

	Engine management / emissions defect warning light This indicates an ‘Engine Management System' malfunction on either petrol or diesel engined vehicle. Normally this will relate to any component that will impact on the emissions of the vehicle. Legislation ensures that the ‘driver' is aware should a fault occur. It may be possible to drive the vehicle to the repairing garage, often in limp-home-mode; although the fault should be checked with a scan tool prior to driving. The lamp may be continuously illuminated or flashing – manufacturer specific functionality. When the fault is diagnosed with a Code Reader, the length of time that the MIL has been illuminated will be recorded in distance run with the light on. Failing to rectify this fault in a timely manor may cause further damage especially to the catalytic convertor.
	Engine management fault warning defect This is an alternative lamp to the one shown above and has identical functionality.
	Glowplugs on (lit) Engine management defect(flashing) warning light This lamp is specific to diesel engines only. The glowplug light will illuminate when the glowplugs are operating. This is normally prior to startup on a cold engine. If the engine is struggling to start from cold and the lamp does not illuminate when the ignition is first switched on then there could be a fault with the glowplug system. On some manufacturer's systems the glowplug lamp has further functionality and if permanently illuminated or flashing then this indicates a diesel fuel injection fault. A third function on some VAG vehicles is when lit in conjunction with the diesel particulate filter warning lamp indicates the condition of the filter. See text for particulate filter lamp.
	Anti-lock braking system (ABS) defect warring light This indicates a malfunction in the ABS system, under these conditions the system will revert back to conventional braking and the anti-skid functionality will be lost. As long as no further lamps are illuminated it is normally safe to drive the vehicle to the nearest vehicle repairer. As with most of the indicator lamps, specialist scan tools will be required to interrogate the system and retrieve the fault codes and look at ‘live data' in order to diagnoses, repair and reset the system. If a vehicle is presented for an MOT test with the lamp on permanently , or not functioning correctly when the ignition is turned on and the vehicle performs a functionality test prior to turning off the light, then the vehicle will fail the MOT test . The testing station will have data that informs the tester when the light should go out, as this will differ between different vehicle manufacturers.
	Electronic stability program (EPS) defect warning light The EPS lamp may flash when the system is in operation (wheel spin / skid prevention). Should the lamp stay whilst the vehicle is driving this will either indicate that the driver has manually turned the system off or there is a fault in the system. The functionality is not dissimilar to that of the ABS and the vehicle can be driven to the nearest repairer for diagnostics.
	Airbag or belt tensioner system defect warning light This lamp indicates that there is a fault in either an air bag or a seat belt tensioner, (before taking the vehicle to a repairer ensure that this is not indicating that the vehicle owner has turned off the passenger air bag to fit a child seat as sometimes this lamp will also indicate this). Should the lamp stay lit once the vehicle is moving then the vehicle needs to be checked with the necessary diagnostic equipment. Unlike the ABS fault warning light, the SRS light is not part of the MOT test. The tester may however ‘advise' the customer that a fault exists and should be rectified as soon as practicable.
	Electro-mechanical steering system defect warning light This lamp indicates a fault in the electro-mechanical assisted steering system. The steering may become very heavy and the driver may struggle to turn the steering wheel comfortably and thus require the vehicle to be recovered into a repairer. As with most systems an intermittent fault may be reset by turning off the vehicle and restarting it; although this will still need to be checked to prevent future breakdowns. On some systems it may also be worth checking the power steering hydraulic fluid level.
	Diesel particulate filter system defect warning light This symbol indicates a fault on the diesel particulate filter. This filter removes particles of ‘soot' from the exhaust emissions and is prone to become blocked / partially blocked if the vehicle is used on short runs. If the light comes on and stays on then it may be possible to ‘regenerate' the filter by driving the vehicle at a preset speed / engine revs as per the manufacturer's handbook instructions. If this lamp fails to go out after a drive cycle then take the vehicle immediately to a repairer to diagnose the fault as leaving the vehicle in this state will invariable put the vehicle into a reduced power or no power state and require the vehicle to be recovered into the repairer. VAG use the engine management warning light and the glowplug warning light in conjunction with the particulate filter light to highlight the level of blockage of the filter and whether the drive regeneration is possible or it needs to go to a vehicle repairer.
	Immobiliser / key recognition system defect warning light This indicates that either the chip within the key has not been recognised by the key reader or there is a fault with the key reader itself. Either way the vehicle will / may crank and fail to start or even fail to crank depending on the system; during the attempt to start the vehicle this symbol may stay illumined or flash. If the key has been dropped and come apart it is worth checking that the chip / transponder has been refitted into the key or try a spare key. On some system it is worth removing the steering cowling and try disconnecting and reconnecting the key reader sensor multiplug (with the ignition off). Some VAG vehicle will start and run for a few seconds before cutting out if the key is not recognsied. Re-synchronisation can occasionally be performed by leaving the ignition on for 10 minutes. Any faults with this system will invariable require the vehicle to be recovered. Often due to the sensitive nature of this system only the main dealer can fix this system, although it is worth checking with independent diagnostic experts as well. The vehicle registration document will be required as proof of ownership.
	Alternator charging system defect warning light Although this symbol represents a battery this is in fact a charge warning lamp controlled either directly by the alternator or by the engine control module (ECM). When the ignition is switched on the light should illuminate and once the engine has started the light should go out. This indicates that the function of the warning light is working (invariable the vehicle's alternator / charging system is operating correctly). Naturally if the light stays on there is a fault that needs rectifying as soon as possible because the vehicle's battery will discharge leading to either non-start or cutting-out of the vehicle. Other than checking any charging fuses, or visually checking to ensure the alternator drive belt is still in place, test equipment will be required to confirm the fault. Many vehicles breakdown because the lamp becomes non-functional and the visual warning is lost – the driver should always check that the light comes on as soon as the ignition is switched on and goes off once the engine is running.
	Engine oil pressure low warning light This light should go out within a few seconds of the engine starting if not immediately. The light indicates that the oil pressure switch has not seen adequate pressure within the oil gallery of the engine to directly put the dash board warning light out or via an ECM. The engine should be stopped immediately and check the engine oil level as per the instructions in the owner's handbook. If the level is low top up and re-start the engine; if the level is fine then recovery the vehicle to a repairer for an oil pressure / system diagnostic check. Under no circumstances should the vehicle be driven with this light illuminated. Some system will prevent engine damage by cutting the engine off should there be inadequate pressure. The system may have a separate lamp for oil pressure and oil level – check with the owner's handbook.
	Coolant temperature too high warning light This lamp indicated that the engine coolant temperature has exceeded a preset threshold and is therefore too high. On some systems that don't have a coolant temperature gauge this is often the first indication that the engine is too hot. Stop the vehicle immediately (where safe and legal to do so following safety precautions). It may be possible to allow the engine to cool considerably and then check the coolant level; never release the expansion tank or radiator cap when the engine is hot as this is potentially very dangerous and could result in sever burns. If the coolant level is low then it may be possible to temporally repair the vehicle by topping it up although it will need to go to the nearest repairer to investigate the reason for the coolant loss. Do not continue to drive a vehicle with a coolant leak or continue to overheat the engine as this can cause extensive / expensive damage to the engine.