Drivers often panic when a dashboard lamp flickers, but not every light signals a looming disaster. a recent study by car‑diagnostic specialist Carly , which examined 8.5 million fault codes over the last six months, breaks down which symbols demand immediate action and which are merely informational. The findings, shared with the Daily Mail and This is Money, also estimate average repair bills for the most common alerts.

Carly’s data shows red lights cost an average £1,200 to fix

According to the RAC, a red warning typically indicates a potentially dangerous issue that requires the driver to stop as soon as safely possible. Carly’s dataset confirms this urgency: the top three red‑light fault codes – engine overheating, brake system failure, and air‑bag deployment fault – each carried repair costs ranging from £800 to £2,300, with a mean expense of £1,200 per incident.

The analysis also highlights that red alerts are far less frequent than amber ones, appearing in just 4 % of the 8.5 million checks. Yet their rarity amplifies the financial impact, as drviers often defer maintenance until the problem becomes critical.

Amber warnings top the list of most‑common dashboard alerts

Amber icons, which the RAC describes as “needs investigation but not urgent,” dominated Carly’s findings, showing up in 27 % of all diagnostic checks. The most prevalent amber codes related to the tyre‑pressure monitoring system, the emissions control valve, and the fuel‑level sensor. Average repair bills for these issues hovered between £120 and £350, considerably lower than red‑light fixes but still enough to disrupt a busy schedule.

Because amber lights are so common, many drivers ignore them, assuming the problem will resolve itself.. Carly warns that repeated amber alerts can evolve into red‑light emergencies if left unchecked, especially for emissions‑related faults that may trigger engine damage.

Green, blue and white lights are merely status indicators

The study confirms that non‑warning colours – green, blue or white – never signal a malfunction. Instead, they inform the driver that a system is active, such as high‑beam headlights or cruise control. Carly’s team found that these symbols appeared in 69 % of the checks and incurred no repair costs, underscoring the importance of colour‑coding for driver reassurance.

Nevertheless, the researchers note that some drivers misinterpret these benign lights as problems, leading to unnecessary service visits and wasted time.

Which fault codes remin under‑reported?

Despite the breadth of Carly’s dataset, the analysis could not capture every possible fault. two notable gaps are the intermittent electrical gremlins that trigger the “electronic stability control” warning and the rare “transmission oil pressure” alert, both of which were reported in fewer than 0.1 % of cases. As the source says, “the report says” these low‑frequency codes may be under‑represented because owners often ignore them until a complete failure occurs.

Another unanswered question is how emerging electric‑vehicle dashboards, with their own suite of colour‑coded alerts, will compare to the traditional internal‑combustion data presented here.

What drivers should do the next time a light flashes

When a red lamp ignites, the RAC advises stopping safely and calling a qualified mechanic – a step reinforced by Carly’s cost analysis, which shows that early intervention can prevent repair bills from soaring above £2,000. For amber warnings, a quick diagnostic scan at a reputable garage can often resolve the issue for under £200.

Finally, drivers are encouraged to familiarize themselves with their vehicle’s owner manual, as the specific meaning of each symbol can vary between makes and models.. Understanding the colour hierarchy and the most common fault codes can turn a moment of panic into a routine maintenance check.