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Warning lights and alertsUrgency: As soon as possible

Overheating or temperature warning light: causes and the faults that trigger it

The red temperature warning light, a thermometer over wavy lines, warns that the engine is overheating or that there is a serious fault in the cooling system, and RACE warns that carrying on driving can cause serious engine damage. You need to slow down, stop somewhere safe, switch the engine off and never open the coolant reservoir while it is hot. The most common causes are low coolant due to a leak, a thermostat stuck closed, a failing water pump, a blocked radiator or a fan that does not switch on.[1][2][3]

Colour: red. Symbol: thermometer over wavy lines (coolant).

52 documented faults cause it in 46 engines. The most important:

What to do now

As soon as possible

Stop as soon as you can and switch the engine off. Do not open the coolant reservoir cap while it is hot. If coolant is missing, do not set off again until you have found the leak.

What it means

The temperature needle climbs towards the red zone or the coolant warning light comes on. It usually points to a lack of coolant, a leak, or a failing thermostat or water pump. Driving on can warp the cylinder head or damage the gasket.

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

62 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. Low coolant due to a leak

    Common cause

    This is the first cause on RACE's list and the one Autodoc Club names as the main one. The level drops through leaks in the hoses, the radiator, the water pump or the expansion tank, and if the system does not seal properly the fluid can also evaporate. According to RACE, the yellow or orange warning light indicates a low coolant level.[1][2][3][4]

  2. 2. Thermostat stuck closed

    Common cause

    The thermostat regulates the flow of coolant between the engine and the radiator. If it sticks closed, RACE explains that the temperature climbs relentlessly above 90 ºC and can end in overheating and serious damage; if it sticks open, the engine takes longer to warm up and uses more fuel, but this is less urgent. Autopista links it to a rapid rise in temperature.[1][3][5][6]

    Faults with with the thermostat and cooling system

  3. 3. Radiator fan that does not switch on

    Possible cause

    RACE explains that the fan should switch on when the engine exceeds roughly 94 ºC and that, if it fails, the car overheats mainly in traffic jams, in town or at idle. Among the causes of failure it lists a blown fuse, a faulty relay, the fan motor, faulty sensors and electrical supply problems.[3][4][7]

  4. 4. Faulty water pump

    Possible cause

    If the pump does not circulate the coolant, the engine overheats because it does not receive enough flow. RACE also lists fluid leaks, noises heard from the cabin and the temperature warning light as symptoms, and links wear to using water instead of coolant.[1][8]

    Faults with with the water pump

  5. 5. Blocked or damaged radiator

    Possible cause

    RACE points out that over the years and kilometres the radiator gets dirty, and that rust and impurities stop the coolant flowing as it should; in its guide to the warning light it includes this among the causes, alongside a damaged radiator. Autodoc Club adds radiator leaks caused by impacts.[1][3][4]

  6. 6. Insufficient or unsuitable oil

    Possible cause

    RACE includes among the causes of overheating a low oil level, because oil both lubricates and cools, and the use of an oil other than the one the manufacturer specifies. Autodoc Club also cites a lack of oil, which reduces heat dissipation.[2][4]

    Faults with with oil consumption

  7. 7. Faulty temperature sensor

    Uncommon

    RACE includes a faulty temperature sensor among the causes of the warning light, which explains why the warning can appear without a real cooling fault; in the case of the fan it also cites faulty sensors as a reason it does not switch on. The sources do not explain how to tell a faulty sensor from genuine overheating without a diagnosis.[1][7]

    Faults with with the engine sensors

  8. 8. Damaged head gasket

    Uncommon

    RACE includes it among the causes of the warning light and also presents it as a consequence of carrying on driving while overheated. Among its symptoms it lists a temperature higher than normal, heavy white smoke, coolant loss without a clear leak, oil that looks like milky coffee and bubbles in the expansion tank; Autodoc Club adds milky coolant.[1][2][4][9]

    Faults with with the head gasket

Depending on what you notice

Why is my car engine overheating?

RACE explains that an engine runs at around 90 ºC and that, to stay there, the cooling system has to work at 100%. It overheats when something fails: its list includes low coolant, low or unsuitable oil, the thermostat, the water pump, a blocked radiator and the fan. Autodoc Club names lack of coolant as the main cause.[2][3][4]

My car overheats but isn't losing coolant

Losing fluid is not the only cause. RACE points out that the warning light can come on even when the level is correct if the thermostat is stuck closed, the fan does not switch on, the pump does not circulate the coolant, the radiator is blocked or the sensor fails; the fan problem is noticeable mainly in traffic jams, in town or at idle. And with a damaged head gasket, coolant can be lost without an obvious leak.[1][7][9]

The car temperature light: red, blue or yellow

RACE distinguishes three colours on the same thermometer-over-waves symbol: blue usually means the engine is cold, yellow or orange that the coolant level is low, and red that the temperature is excessive or that there is a serious system fault. Red is the one that requires you to stop without delay.[1][3]

The temperature warning light comes on while I'm driving

RACE recommends slowing down and avoiding hard acceleration, finding a safe, level place, switching off the engine and waiting about 15 minutes before opening the bonnet; with the engine cold you check the coolant level, never by opening the reservoir while hot because the fluid is under pressure. In other guides it sums up that, if the red warning light comes on, you should pull over straight away and call breakdown assistance.[1][2][3]

What to check first

  1. Reduce your speed, avoid accelerating hard and find a safe, level place to stop; switch off the engine without waiting for the needle to reach the red zone.[1][7]
  2. Wait about 15 minutes before opening the bonnet and do not open the expansion tank while the system is hot: the fluid is under pressure and can cause serious burns.[1][7]
  3. With the engine cold, check that the coolant level is between the minimum and maximum marks on the reservoir.[1][7]
  4. Look for stains of yellow, pink or other coloured fluid under the car and check whether the hoses and radiator are dripping: they indicate a leak.[1][2]
  5. If fluid is missing, top up with compatible coolant (check the manual). If you have topped up with water, RACE says the system will need to be bled and refilled with antifreeze.[1][3]
  6. If the level is correct and the warning light comes on again, or you see signs of a leak, do not keep driving: call breakdown assistance and ask for the thermostat, fan, pump, radiator and sensor to be checked.[1][2][5][7]

Can I keep driving?

Urgency: As soon as possible

No. With the red warning light you must stop as soon as possible and safely, switch off the engine and, if in any doubt, call breakdown assistance: RACE warns that ignoring the warning can cause serious engine damage, such as a warped cylinder head, gasket failures and even engine breakdown. For code P0217 (engine over-temperature), Autodoc Club gives the same advice: stop the vehicle immediately.[1][2][10]

How much it costs to fix

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

RepairPrice
Replacing the thermostat, part (around 40 euros) and labour, according to RACE (approximate figure)[5]€200
New water pump, part only, according to RACE (excluding labour and timing belt replacement)[8]€130
Skimming the cylinder head warped by excess temperature, according to RACE (not always possible; it does not say whether removal is included)[2]€100
Replacing the cylinder head, from this figure according to RACE (the price varies by car)[2]€1,000

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 2.0/2.2 D-4D[11][12]

  2. Source for the symptom in the 1.6 EcoBoost[13]

  3. Source for the symptom in the BMW M54[14][15]

  4. Source for the symptom in the 1.2 / 1.4 / 1.8 i-VTEC[16]

  5. Source for the symptom in the Porsche V8 and V6 (Cayenne and Panamera)[17]

  6. Source for the symptom in the 1.4/1.6 VTi[18]

  7. Source for the symptom in the 1.6 THP[18]

  8. Source for the symptom in the 0.9 TCe[19]

  9. Source for the symptom in the Rover K-Series[20][21]

  10. Source for the symptom in the 3.0 TDI V6[22]

  11. Source for the symptom in the 1.0 EcoBoost[23]

  12. Source for the symptom in the BMW N20[24]

  13. Source for the symptom in the OM654[25]

  14. Source for the symptom in the 2.2 dCi and 3.0 dCi V6[26]

  15. Source for the symptom in the 1.6 EcoBoost[13]

  16. Source for the symptom in the 1.6 TDI[27]

  17. Source for the symptom in the 1.4 and 1.6 TU3/TU5[28]

  18. Source for the symptom in the 1.4 and 1.6 8v[29]

  19. Source for the symptom in the 1.2 16v[30]

  20. Source for the symptom in the Rover K-Series[31]

  21. Source for the symptom in the 1.8 Hybrid[32][33]

  22. Source for the symptom in the 1.2 TDI[34]

  23. Source for the symptom in the 1.4 16v and 1.6 MPI/FSI[34]

  24. Source for the symptom in the 1.4 TDI[34]

  25. Source for the symptom in the 1.2 and 1.4 TSI[35]

  26. Source for the symptom in the OM651[36]

  27. Source for the symptom in the 2.0 TSI / TFSI[27]

  28. Source for the symptom in the BMW N52 / N53[37][38]

  29. Source for the symptom in the BMW N54/N55[39]

  30. Source for the symptom in the M111[40]

  31. Source for the symptom in the 1.4 Turbo[41]

  32. Source for the symptom in the 1.0 VVT-i[42]

  33. Source for the symptom in the 1.0 TSI / 1.5 TSI[43]

  34. Source for the symptom in the Audi 3.0 TFSI V6[44]

  35. Source for the symptom in the BMW B48 / B38[45]

  36. Source for the symptom in the BMW B58[46]

  37. Source for the symptom in the 1.25/1.4/1.6 Ti-VCT[47]

  38. Source for the symptom in the M270/M274[48][49]

  39. Source for the symptom in the 2.2 CDI (OM646)[50]

  40. Source for the symptom in the 1.6 and 1.8 Ecotec 16v[51]

  41. Source for the symptom in the Porsche V8 and V6 (Cayenne and Panamera)[52]

  42. Source for the symptom in the 1.4 and 1.6 TU3/TU5[53]

  43. Source for the symptom in the Rover K-Series[54]

  44. Source for the symptom in the 1.2 Turbo[33]

  45. Source for the symptom in the 1.4, 1.6 and 1.8 VVT-i[11]

  46. Source for the symptom in the 1.6 Dual VVT-i[55]

  47. Source for the symptom in the 2.0 and 2.4 VVT-i[56][57]

  48. Source for the symptom in the Drive-E gasolina[58]

  49. Source for the symptom in the 1.4 16v and 1.6 MPI/FSI[59]

  50. Source for the symptom in the 1.8 T 20v[60]

  51. Source for the symptom in the M272/M273[61]

  52. Source for the symptom in the 1.2 Dualjet and 1.2 VVT[62]

Which cars it appears in

These faults affect 46 engines. We have documented 300 models from 28 makes with some of the affected versions: open yours to see all its faults.

Engines

Cars with the affected versions

Overheating: causes in your car

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

Audi 33
BMW 38
Citroën 11
Cupra 3
Dacia 4
DS 2
Ford 12
Honda 3
Infiniti 2
Land Rover 1
Lexus 2
Lotus 2
Mercedes-Benz 33
MG 5
MINI 6
Nissan 1
Opel 12
Peugeot 14
Porsche 4
Renault 12
Rover 4
Seat 13
Škoda 16
Smart 2
Suzuki 2
Toyota 20
Volkswagen 33
Volvo 10

Overheating by brand

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

Can I keep driving with the red temperature warning light on?

No. RACE says that if the red temperature warning light comes on, you must stop immediately and call breakdown assistance, because continuing with an overheated engine can cause serious engine damage. Autodoc Club says the same about code P0217: stop the vehicle immediately.[1][2][10]

What does it mean if the temperature light is blue or yellow?

According to RACE, a blue light usually means the engine is cold, and a yellow or orange one that the coolant level is low. Only red signals excessive temperature or a serious system fault.[1]

Can I open the reservoir cap with the engine hot?

No. RACE warns that you must not open the coolant reservoir while the system is hot, because the fluid is under pressure and can cause serious burns. It recommends waiting about 15 minutes before opening the bonnet; Autodoc Club, which describes how to remove the cap carefully, talks about waiting 30 to 45 minutes.[1][4][7]

What happens if I keep driving with the engine overheated?

RACE warns of serious damage such as a warped cylinder head, head gasket failures and even engine breakdown, and in its guide to overheating it speaks of a very serious failure, such as a seized engine. Autodoc Club adds a cracked cylinder head, piston ring failure and a completely seized engine.[1][2][4]

Can I top up with water if coolant is low?

RACE does not recommend it as a permanent solution: it explains that the car does not use water to cool the engine but a specific fluid, and that if you top up with water you need to bleed the system and refill it with antifreeze. In its guide to the warning light it allows distilled or deionised water only if you are unsure which fluid is the right one.[1][3]

Why does my car only overheat in traffic jams or when stationary?

According to RACE, this is the typical symptom of a fan that does not switch on: the car overheats mainly in traffic jams, in town or at idle, and among the causes it lists a blown fuse, a faulty relay, the fan motor or faulty sensors. If the needle rises while the car is stationary, you should have a garage check it as soon as possible.[7]

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. ¿Qué es el testigo del líquido refrigerante y qué hacer si se enciende?RACE · Motoring press · published 27 May 2026 · consulted 4 October 2026 · in Spanish
  2. Sobrecalentamiento del motor: ¿por qué se produce y qué consecuencias tiene?RACE · Motoring press · published 19 January 2023 · consulted 4 October 2026 · in Spanish
  3. ¿Por qué se calienta el coche?RACE · Motoring press · published 24 July 2023 · consulted 4 October 2026 · in Spanish
  4. ¿Por qué se calienta el coche?: síntomas y consecuencias del sobrecalentamiento del motorAutodoc Club · Technical documentation · published 22 November 2021 · consulted 4 October 2026 · in Spanish
  5. Termostato del coche: síntomas y averíasRACE · Motoring press · published 11 March 2022 · consulted 4 October 2026 · in Spanish
  6. ¿Para qué sirve el sistema de refrigeración del motor y cómo mantenerlo?Autopista · Motoring press · published 12 September 2025 · consulted 4 October 2026 · in Spanish
  7. ¿Cómo saber si el ventilador del coche no funciona?RACE · Motoring press · published 12 August 2026 · consulted 4 October 2026 · in Spanish
  8. Bomba del agua del coche: síntomas y averíasRACE · Motoring press · published 5 May 2021 · consulted 4 October 2026 · in Spanish
  9. ¿Se puede circular con la junta de culata mal?RACE · Motoring press · published 15 September 2026 · consulted 4 October 2026 · in Spanish
  10. Código OBD2 P0217: Sobretemperatura del MotorAutodoc Club · Technical documentation · consulted 4 October 2026 · in Spanish
  11. Toyota Avensis (2003-2009) : fiabilité, pannes et rappelsFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  12. Toyota RAV4 (2013-2019) : fiabilité, pannes et rappelsFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  13. Ford EcoBoost engineWikipedia · Other source · consulted 27 September 2026
  14. M54 Engine ProblemsBMW Tuning · Technical documentation · consulted 5 October 2026
  15. BMW M54 Engine Guide: Reliability, Common Problems & Tuning PotentialEuro Premium Parts · Technical documentation · consulted 5 October 2026
  16. Honda Civic 8 (2005-2011): alle bekannten Probleme & KrankheitenGebrauchtwagenberater.de · Other source · consulted 27 September 2026 · in German
  17. Porsche Cayenne Coolant Pipe Failure: Causes, Symptoms, and Repair CostsForeign Automotive (taller de Ontario, Canadá) · Other source · consulted 9 October 2026
  18. Liste des moteurs qui ont des soucis de refroidissementFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  19. Fiabilité des 0.9 TCeFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  20. Guía de compra del MG TF de segunda manoDiariomotor · Motoring press · published 7 November 2023 · consulted 8 October 2026 · in Spanish
  21. MG ZR (used car review)Auto Express · Motoring press · published 28 September 2004 · consulted 8 October 2026
  22. Audi A6 C6 (4F): Typische Probleme & SchwachstellenGebrauchtwagenberater.de · Motoring press · published 9 September 2022 · consulted 9 October 2026 · in German
  23. Ford EcoBoost engines: reliability, problems and should you buy one?Carbuyer · Motoring press · consulted 26 September 2026
  24. BMW-Rückruf: 720.796 Fahrzeuge in den USA betroffen (Wasserpumpe)Auto Motor und Sport · Motoring press · published 21 August 2024 · consulted 27 September 2026 · in German
  25. Mercedes-Benz GLC (X253): Alle typischen Probleme & MängelGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  26. Renault Espace et Vel Satis : le 3.0 V6 dCi surchauffeL'argus · Motoring press · published 22 June 2010 · consulted 5 October 2026 · in French
  27. Bomba de agua del coche, qué es, función y cuándo cambiarlaAutopista.es · Motoring press · published 10 June 2026 · consulted 26 September 2026 · in Spanish
  28. Tous les problèmes sur Citroën Xsara (témoignages)Fiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
  29. Fiabilité et pannes de la Renault Clio 2Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  30. Fiabilité et pannes du Dacia SanderoFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  31. Choosing the correct K Series Head Gasket KitDMGRS · Technical documentation · consulted 8 October 2026
  32. Toyota Prius 4 : fiabilité, pannes et rappelsFiches-auto.fr · Motoring press · consulted 26 September 2026 · in French
  33. Toyota Auris : fiabilité, pannes et rappelsFiches-auto.fr · Motoring press · consulted 26 September 2026 · in French
  34. Bomba de agua del coche: la avería de más de 1.500 euros que arrastra la correa de distribuciónMotor16 · Motoring press · published 21 September 2026 · consulted 27 September 2026 · in Spanish
  35. VW Golf 7: Probleme, Mängel & Schwachstellencarwiki.de · Other source · consulted 26 September 2026 · in German
  36. Culata fisurada: síntomas, diagnóstico y coste real de reparaciónCajas y Motores · Motoring press · consulted 26 September 2026 · in Spanish
  37. Problemas BMW N52Total Renting · Other source · consulted 5 October 2026 · in Spanish
  38. BMW N52 Engine ProblemsBMW Tuning · Other source · consulted 5 October 2026
  39. BMW N55 Typische Probleme und HaltbarkeitGebrauchtwagenberater · Motoring press · published 23 February 2025 · consulted 5 October 2026 · in German
  40. Mercedes M111: Typische Probleme und HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  41. Opel Zafira Tourer : fiabilité, pannes et rappelsFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  42. Fiabilité de la marque Toyota (Aygo)Fiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  43. Nivel de refrigerante por debajo del mínimo ya?Club Skoda Karoq (foro) · Owners' forum · consulted 26 September 2026 · in Spanish
  44. Common Problems of Audi A6 C7 3.0 TFSI: A Comprehensive GuideEuro Auto Pro (blog de taller, Australia) · Other source · published 6 October 2024 · consulted 9 October 2026
  45. Motor BMW B48: defectos, mantenimiento y guía de compraRecambios y Accesorios BMW (blog) · Technical documentation · consulted 27 September 2026 · in Spanish
  46. Der BMW B58 Motor | Technische Daten, Probleme, Haltbarkeit & Liste der FahrzeugeCarWiki.de · Technical documentation · consulted 9 October 2026 · in German
  47. Fiabilité et pannes Ford FiestaFiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
  48. Mercedes M274: Typische Probleme & HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  49. Mercedes M270: Typische Probleme & HaltbarkeitGebrauchtwagenberater · Motoring press · consulted 27 September 2026 · in German
  50. Fiabilité 220 CDIFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  51. Fiabilité Opel Insignia (A): pannes et témoignagesFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  52. Porsche Cayenne: typische Probleme und Diagnose (957/958)KFZ Dietrich (taller, Alemania) · Other source · published 15 May 2026 · consulted 9 October 2026 · in German
  53. Tous les problèmes sur Peugeot 206 (témoignages)Fiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
  54. Cooling and heating (K-Series: ZR, ZS, ZT, MGF, TF)MGOC Spares · Technical documentation · consulted 8 October 2026
  55. Toyota Auris (2007-2012) : fiabilité, pannes et rappelsFiches-auto.fr · Motoring press · consulted 27 September 2026 · in French
  56. Toyota RAV4 III 2.0 essence VVT-i 152ch : longévitécarverif.fr · Other source · consulted 5 October 2026 · in French
  57. Common 2AZ-FE Engine Problems and How to Fix ThemThe Auto Insider Blog · Other source · consulted 5 October 2026
  58. Fiabilité et pannes Volvo V40Fiches-auto.fr · Other source · consulted 27 September 2026 · in French
  59. Fiabilité Skoda Octavia (1997-2004) - pannes moteur, boîte...Fiches-auto.fr · Owners' forum · consulted 27 September 2026 · in French
  60. Fiabilité et pannes Volkswagen PassatFiches-auto.fr · Other source · consulted 27 September 2026 · in French
  61. 4 Common Mercedes M272 Engine Problems8020 Automotive · Technical documentation · consulted 5 October 2026
  62. Suzuki Splash (2008–2014) – Bekannte Probleme & KrankheitenGebrauchtwagenberater.de · Motoring press · consulted 27 September 2026 · in German