What’s the first thing you think when a new warning light pops up on your VW’s dashboard?
Panic for your safety? Worry for your bank account? Irritation at your day being interrupted?
First things first. Take the time to learn your warning lights in advance and what the different colours mean. That way, you’ll be prepared long in advance, and you’ll know exactly when your car is telling you, ‘Stop now’.
Here at Sunset VW in Derby, we get cars coming in with warning lights on the dashboard all the time. Some are serious. Some aren’t. Here’s our plain-English guide to a few of the most common we see in VWs, and what to do about them.
The traffic light rule of warning light colours
Before we dive into specifics about different VW warning lights, here’s a simple rule of thumb:
- Red light – stop the car as soon as it’s safe. These mean something is seriously wrong.
- Flashing amber/orange light – again, stop the car as soon as you can.
- Amber/orange light – drive with caution and get it checked ASAP.
- Green or blue light – information only. These aren’t warnings.
Now, let’s take a look at what those various lights actually mean.
Engine management light (amber engine symbol)
This light looks like a small outline of an engine. If it comes on and stays on in amber, it means your VW’s engine control unit (ECU) has detected a fault. These days, it’s most often related to the emissions system, but it could also point to issues with the fuel or exhaust systems.
In most cases, it’s still safe to drive short distances, but you’ll want to book a diagnostic check as soon as possible. Ignore it, and it could lead to reduced power, higher fuel use, limp mode or even long-term damage.
If this light is flashing, pull over as soon as it’s safe and switch off the engine. A flashing engine light usually indicates a severe misfire, which could impact your ability to drive safely and damage the catalytic converter, an expensive repair.
Coolant temperature warning (red thermometer in waves)
If the thermometer light comes on red, your engine is overheating. It could be due to low coolant, a broken thermostat or something more serious like a failed water pump. Sometimes, it’s also caused by a faulty sensor.
Stop the car as soon as it’s safe. The longer you drive with an overheating engine, especially at high speeds or with constant acceleration and deceleration, the higher the risk of severe and potentially irreparable internal damage. These can include blown head gaskets or even engine seizure. Let the engine cool, check the coolant level (only when it’s cool), and call us if you’re unsure what to do next.
Oil pressure warning (red oil can)
The oil pressure light is often misunderstood. Although you might instinctively think it’s about oil level, that isn’t strictly true. It’s actually about oil pressure. It’s related, in the sense that low volume means low pressure, but there could be other causes, too.
If this red light comes on, it means the oil isn’t circulating properly. As a result, your engine isn’t getting the lubrication it needs. The cause could be low oil (fixed with a top-up), but there could also be a problem with the oil pump or a leak somewhere in the system.
You should stop immediately, as soon as it’s safe to do so. Continuing to drive could result in complete engine failure. Check your oil level and call recovery if the level is fine but the light remains on. Regular servicing should help keep problems like this at bay.
Brake system warning (red circle with exclamation mark or ‘P’)
Any brake problems should be flagged during an MOT, but sometimes they develop unexpectedly. The brake system warning light on your VW’s dashboard could mean a few different things:
- The handbrake is engaged. You’ll know this one. Just disengage it if driving, and the light should turn off. It’s fine if you’re parked.
- The brake fluid is low.
- There’s another serious brake system fault.
Don’t drive if the light stays on, or until you’ve confirmed it’s not a fluid issue or something more serious. The last thing you want is to be driving and suddenly find you have no brakes. Although this is rare, it’s still possible. Check your brake fluid level in the reservoir under the bonnet. If it’s too low (below ‘MIN’), it’ll have air bubbles in it, which will seriously impact your stopping ability. If in any doubt, get professional help right away.
ABS warning light (amber circle with ‘ABS’)
Your anti-lock braking system (ABS) has developed a fault. The ABS is that juddering through the pedal when you slam the brake on in an emergency. Your regular brakes will still work (see the previous warning light), but the anti-lock function won’t, meaning your wheels could lock up under hard braking. That’s dangerous, and means longer stopping distances and very little steering control if you need to make an emergency stop.
You don’t need to stop immediately, but drive cautiously and have it checked as soon as you can. If you see this alongside the red brake light, stop immediately. Both systems may be compromised.
Diesel particulate filter (amber light with puff of smoke)
This one’s unique to diesels and indicates the diesel particulate filter (DPF) is getting clogged with soot. Most of the time, the light comes on because the car hasn’t had a proper run. DPFs need motorway speeds for the system to burn off soot.
Try a 15- or 20-minute drive at 60+ mph in fourth or fifth gear. Focus on getting the revs reasonably high, but not to the redline. The objective here is to get the DPF itself hot, thanks to hot exhaust gases, to burn off any soot material that might be clogging it.
If the light stays on, it could need a manual regeneration or cleaning.
Battery warning light (red battery symbol)
The battery warning light doesn’t necessarily mean your battery is flat, especially if the car’s running. It’s actually an indication of an issue in the charging system. The most likely causes are a failing alternator or a loose auxiliary drive belt.
Drive straight to a garage or pull over and call your breakdown service. If the alternator stops running completely, your car’s electronics will stop working. That includes the spark plugs and fuel pump that power the engine, so your vehicle will simply stop running. If you’re still moving, you’ll be left with almost no control. The red warning light doesn’t necessarily mean that’s going to happen, but it is a possibility.
Sometimes, the root cause is complex thanks to the vast array of electronics in modern vehicles. As such, we may need to do some diagnostics work to find and fix the fault.
Tyre Pressure Monitoring System (amber horseshoe with exclamation mark)
This system monitors the pressure in all tyres and alerts you to significant drops. If this comes on:
- Stop and check your tyre pressures.
- Look for any visible damage or punctures.
- If you’ve inflated or changed tyres recently, the system might just need resetting.
There are two types of TPMS: active and passive.
- Active TPMS has pressure sensors built into the valves. These are frighteningly accurate, and when the TPMS comes on, there’s usually a pressure problem.
- Passive TPMS uses the ABS sensors. These monitor the rotation speeds of wheels across an axle. If one wheel is turning faster than another when you’re driving straight, you likely have a difference in pressures (that is, a flat tyre). This triggers the warning light. Passive TPMS isn’t as accurate as active TPMS, but you should still check all your tyre pressures and look for punctures before continuing to drive slowly.
In both cases, problems with the sensor itself could also make the warning light illuminate on your VW’s dashboard. Refer to your manual for how to reset the TPMS, or pop into our service centre and we’ll sort it. If one of your tyres is flat and has been damaged, you need a new one to stay safe.
Airbag or SRS warning (amber icon of a person with a circle)
This light means there’s a fault with the airbag system, which could mean they won’t go off in a crash, or go off when they shouldn’t.
Neither of these warrants an immediate emergency stop, but we do suggest going to a garage as soon as possible. This isn’t one you want to ignore. It’s easy to forget about a warning that doesn’t affect your drive right now, until it suddenly does, when you least expect it. And then, the consequences could be extremely severe. Airbag faults should always be diagnosed and repaired by professionals, as they’re safety-critical.
AdBlue warning (amber and then red light that looks like a beaker or exhaust)
Modern diesel VWs use AdBlue to reduce emissions. If the AdBlue level gets low, you’ll get a warning. The warning light on your dashboard is usually amber first, then red if ignored.
If the red light comes on, the engine won’t restart after it’s turned off. You’ll need to top up the AdBlue before you can drive again. We can refill this for you in a jiffy at the workshop, or you can buy approved AdBlue fluid and fill it yourself (refer to your handbook for instructions). Some models may also require a short drive or ignition cycle before the warning resets.
Book a service at Sunset VW
If you’ve got a warning light on your dash and you’re not sure what it means – or how urgent it is – we’re here to help. Drop in or give us a call, and we’ll offer you advice on how to stay safe.
At Sunset VW in Derby, we work exclusively on Volkswagen Group vehicles, so we know the ins and outs of every warning light. Our diagnostic tools are dealer-grade, and our team has decades of experience with Volkswagens of all ages. And just so you know, if a warning light disappears by the time you arrive, we can still read the code history from your VW’s control units.
Get in touch or book a service online today