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Warning lights and alertsUrgency: Garage soon

Glow plug warning light flashing: causes and the faults that trigger it

The coil light, a yellow or orange spiral, is the diesel glow plug warning light: it comes on for a few seconds when you switch on the ignition and then goes out, and that is normal. If it flashes with the engine already running, or appears together with the engine fault light, it is no longer the preheating: it warns of a fault (glow plugs, sensors, EGR or particulate filter, according to the sources) and the car may limit power, so it should be taken to a garage to have the codes read.[1][2][3][4]

Colour: yellow or amber. Symbol: coil or spiral (the heating element of the glow plugs), in yellow or orange.

2 documented faults cause it in 2 engines:

What it means

On many diesels, the glow plug light flashes while the engine is running to warn of an engine management fault: fuel pressure, injectors, EGR or turbo, among others.

General explanation from MotorFiable. How it shows up in each engine, with sources, is in the list of faults.

What to do now

Garage soon

Go easy on the engine and ask for a fault code read-out. Driving like this for a long time can cause more serious damage.

12 sourcesHow we work

Most common causes

From most to least likely according to the sources. Under each cause, the part and the related OBD codes.

  1. 1. Worn or faulty glow plugs

    Common cause

    If one or more glow plugs do not preheat (there is one per cylinder), the light flashes or stays on and cold starting becomes harder. It is a part that loses effectiveness over time and is replaced when it fails; Autodoc Club cites them as the first cause of code P0380. Typical symptoms are slow or uneven cold starting, unstable idle and white smoke.[1][3][4][5][6]

    P0380

  2. 2. Fault in a sensor or in engine management (emergency mode)

    Common cause

    If the control unit is missing information from a sensor and thinks there is a fault, it puts the car into emergency mode: the engine light and the coil light come on and speed is limited. Autofácil links it to failures of various engine management and emissions sensors.[3][7]

    Faults with with the engine sensorsFaults with with the control units

  3. 3. Glow plug relay, fuse, wiring or control module

    Possible cause

    RACE includes the glow plug relay and broken wires in the heating element among the possible repairs. Autodoc Club adds blown fuses, corroded or loose connections and a faulty control unit as causes of codes P0380 and P0670.[1][6][8]

    Faults with with the electrical wiringFaults with with the control unitsP0380P0670

  4. 4. Dirty or faulty EGR valve

    Possible cause

    Autofácil cites the EGR valve among the components usually tied to a continuous flashing of the preheating light, when it does not indicate the start-up process but a possible issue in the system.[3]

    Faults with with the EGR valve

  5. 5. Saturated or faulty particulate filter

    Possible cause

    Like the EGR, the particulate filter (DPF) appears in Autofácil as one of the components related to continuous flashing of the coil light.[3]

    Faults with with the particulate filter

Depending on what you notice

The coil light flashes while I am driving

If the flashing starts with the car already running, it is not the preheating: RACE links it to an engine management fault and Autofácil, when it is continuous, to faults in the EGR, the particulate filter or the sensors. If the car drives normally, the priority is to find a garage that will repair the fault.[2][3]

The engine fault light and the coil light come on

RACE says that if the glow plug light flashes together with the engine fault light, the car should be taken to a garage immediately, because it can go into emergency mode and limit power. In that mode the control unit also limits speed: RACE gives the example of not letting you exceed 80 km/h instead of 120.[1][7]

The coil light comes on when starting

This is normal: it indicates that the glow plugs are working and should go out within a few seconds; in older cars you wait for it to go out before starting. If it stays on for more than 10 or 15 seconds without exceptionally cold weather, the glow plugs may be worn.[2][5][9]

The coil light flashes and the car is hard to start when cold

RACE explains that if the light flashes, a glow plug may not be preheating, which makes the diesel harder to start. Autofácil points out that slower or uneven cold starting is usually one of the first signs that the glow plugs are starting to fail.[1][3]

The coil light flashes on a Seat Ibiza

We have not found a source specific to the Ibiza, a SEAT model, a subsidiary of the Volkswagen group. RACE does describe the case of cars in that group: with the glow plug light flashing in yellow there is usually a power restriction and the engine fault light also appears steady.[1][10]

What to check first

  1. Note when it happens: coming on when you switch on the ignition and going out in a few seconds is normal; if it stays on for more than 10 or 15 seconds without exceptional cold, or flashes with the engine running, it needs checking.[2][9]
  2. See whether the steady engine fault light also appears or whether the car limits power: it is a sign that it has gone into emergency mode.[1][7]
  3. Observe how it starts when cold: slow or uneven starting, unstable idle and white smoke point to the glow plugs.[3][4][9]
  4. Have the codes read with a diagnostic machine through the OBD port. Faults in the glow plug circuit leave codes such as P0380 or P0670; if EGR, particulate filter or sensor codes also appear, the cause may be something else.[1][3][6][8]
  5. Have the fuse, relay and connections of the glow plug circuit checked before replacing parts: Autodoc Club cites them among the causes of codes for this circuit.[6][8]

Can I keep driving?

Urgency: Garage soon

The light coming on for a few seconds at start-up is normal. If it flashes with the engine running or appears together with the fault light, RACE recommends going to a garage as soon as possible and not prolonging use of the car without a diagnosis, because it can go into emergency mode with limited power. If the car drives normally, the priority is to find a technical service to repair it. For a fault in the glow plug circuit (P0380), Autodoc Club says you can normally keep driving with a warm engine, but it should be fixed as soon as possible.[1][2][6]

How much it costs to fix

Indicative prices published by the sources cited; they depend on the car and the garage.

RepairPrice
Replacing the glow plugs at a garage (parts at 10 to 20 euros each plus labour, depending on the model and access, according to Autofácil)[3]€150 – €300
One new glow plug (part only, according to RACE; add one or two hours of labour)[5]€25 – €45

Documented faults that cause it

Specific engine and gearbox faults, from most to least important (severity × frequency). Below each title, how the symptom shows up in that fault.

  1. Source for the symptom in the 2.0 dCi[11]

  2. Source for the symptom in the 2.4 / 2.8 D-4D (GD)[12]

Which cars it appears in

These faults affect 2 engines. We have documented 7 models from 2 makes with some of the affected versions: open yours to see all its faults.

Engines

Cars with the affected versions

Flashing glow plug light: causes in your car

7 cars have several documented faults that cause this symptom. Choose yours to see only those that affect it, by engine and by year.

Nissan 2
Renault 5

Fault codes that may go with it

If you have an OBD reader, the code stored by the control unit helps you work out which system is failing.

Frequently asked questions

What does the coil light on the car dashboard mean?

It is the preheating light on diesels. It comes on when you switch on the ignition while the glow plugs are working and should go out within a few seconds. On modern direct-injection diesels, RACE explains that it no longer usually appears, because the glow plugs act within tenths of a second and there is no need to wait.[2][5]

Can I keep driving if the coil light flashes?

If the car drives normally, RACE says the priority is to find a technical service to repair the fault. If the steady engine fault light is also on, you should go to the garage immediately, and it is not recommended to prolong use without a diagnosis.[1][2]

How much does it cost to replace the glow plugs?

In Spain, Autofácil puts the total at a garage, including labour, at between 150 and 300 euros, with parts at 10 to 20 euros each. RACE speaks of 25 to 45 euros per new glow plug plus one or two hours of labour. The sources do not agree on the price of the part.[3][5]

Will it pass the MOT with the glow plug light on?

Diariomotor warns that the warning lights that appear when the glow plugs fail could lead to failures at the ITV (the Spanish roadworthiness inspection, equivalent to the MOT), even an unfavourable result. It is worth resolving the fault before taking the inspection.[4]

Other symptoms: warning lights and alerts

All symptoms

Has this happened to you? Tell us which fault it was, at how many kilometres and how much you paid: it helps other owners know what to expect. Report your fault.

Sources

Every fact on this page links to its source. If you find an error, let us know.

  1. 1.Esto es lo que pasa si la luz de los calentadores está parpadeando y la de avería motor está fijaRACE · Motoring press · published 16 June 2026 · consulted 2 October 2026 · in Spanish
  2. 2.Se ha encendido un testigo luminoso en el cuadro de instrumentos del coche, ¿qué significa?RACE · Motoring press · published 18 November 2022 · consulted 2 October 2026 · in Spanish
  3. 3.Por qué los diésel necesitan precalentarse y qué significa cuando parpadea esta luzAutofácil · Motoring press · published 19 April 2026 · consulted 2 October 2026 · in Spanish
  4. 4.Cómo detectar que los calentadores de un coche diésel están en mal estadoDiariomotor · Motoring press · published 16 January 2020 · consulted 2 October 2026 · in Spanish
  5. 5.Calentador de un motor diésel, ¿cuál es su función?RACE · Motoring press · published 20 November 2023 · consulted 2 October 2026 · in Spanish
  6. 6.Código de avería P0380 - guía paso a paso para su diagnóstico y resoluciónAutodoc Club · Technical documentation · consulted 2 October 2026 · in Spanish
  7. 7.Mi coche pierde potencia y se queda sin fuerza en las subidas y al acelerarRACE · Motoring press · published 20 January 2023 · consulted 2 October 2026 · in Spanish
  8. 8.Código de avería P0670 - guía paso a paso para su diagnóstico y resoluciónAutodoc Club · Technical documentation · consulted 2 October 2026 · in Spanish
  9. 9.Calentadores de un motor diésel: funcionamiento y averíasDiariomotor · Motoring press · consulted 2 October 2026 · in Spanish
  10. 10.SEAT - Wikipedia, la enciclopedia libreWikipedia · Other source · consulted 2 October 2026 · in Spanish
  11. 11.Anexo:Motores de RenaultWikipedia · Other source · consulted 27 September 2026 · in Spanish
  12. 12.Bujía de precalentamientoWikipedia (español) · Other source · consulted 9 October 2026 · in Spanish