LeaksUrgency: As soon as possible

Brake fluid leak: causes and the faults that trigger it

15 documented faults cause it in 15 cars. The most important:

Critical severity: Recalls for the rear brake hose and the sealing of the handbrake cable · Audi A4 B6
Critical severity: Internal brake fluid leak in the EBS valve block (built May and June 2024) · Citroën C4 X
Critical severity: Wrongly positioned brake hose, with a risk of breakage (built April-December 2019) · DS DS 3 Crossback

What to do now

As soon as possible

Do not keep driving if the pedal sinks or loses firmness: check the reservoir level and take the car to a garage before driving any further.

What it means

Brake fluid escapes from the hydraulic circuit, normally through a hose, a flexible line or a deteriorated seal, and usually leaves stains or drips near a wheel.

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

Reviewed on 5 October 202614 sources How we work

Faults that cause it

Suspension, brake, electronics and other faults on specific cars, from most to least important.

- Critical severityOccasionalFrequency: OccasionalAudi A4 B6Recalls for the rear brake hose and the sealing of the handbrake cablePossible brake fluid leak from the rear hose affected by the 2003 recall.Repair: €0
Source for the symptom in the Audi A4 B6^[1]
- Critical severityOccasionalFrequency: OccasionalCitroën C4 XInternal brake fluid leak in the EBS valve block (built May and June 2024)A drop in the brake fluid level due to an internal leak in the valve block (the notice speaks of an internal leak, not of a puddle visible under the car).
Source for the symptom in the Citroën C4 X^[2]
- Critical severityOccasionalFrequency: OccasionalDS DS 3 CrossbackWrongly positioned brake hose, with a risk of breakage (built April-December 2019)Brake fluid may drip around the wrongly positioned hose, with a resulting drop in the reservoir level and a possible loss of braking effectiveness.
Source for the symptom in the DS DS 3 Crossback^[3]
- Critical severityOccasionalFrequency: OccasionalFord RangerFatigue cracking and deformation of the front brake hosesOn the Raptor, a deformed and damaged hose can leak brake fluid and reduce the performance of the braking system.
Source for the symptom in the Ford Ranger^[4]
- Critical severityOccasionalFrequency: OccasionalMercedes-Benz Citan W415Underbody brake pipe not screwed in properly on cars built in August and September 2016The source describes no prior symptoms; the risk it mentions is loss of brake fluid.
Source for the symptom in the Mercedes-Benz Citan W415^[5]
- Critical severityOccasionalFrequency: OccasionalMercedes-Benz Sprinter 907Front flexible brake hoses damaged by rubbing against the wheel archLoss of brake fluid through the damaged hose, with reduced braking effectiveness and a longer stopping distance.
Source for the symptom in the Mercedes-Benz Sprinter 907^[6]
- Critical severityOccasionalFrequency: OccasionalMercedes-Benz Vito W447Badly fitted brake pipes with brake fluid leak and fire risk (November 2018 to May 2019)Brake fluid leak and, according to the source, longer stopping distances.
Source for the symptom in the Mercedes-Benz Vito W447^[7]
- Critical severityOccasionalFrequency: OccasionalToyota Celica VIICorrosion in the brake master cylinder: brake fluid leakThe master cylinder seal may let brake fluid escape, or a little air may enter the master cylinder, which would lengthen the braking distance.
Source for the symptom in the Toyota Celica VII^[8]
- High severityOccasionalFrequency: OccasionalFord Tourneo CourierBrake pipe fitting touching the fuel tankA brake fluid leak may show up as a softer pedal or reduced braking performance; the source describes no prior symptoms.
Source for the symptom in the Ford Tourneo Courier^[9]
- High severityOccasionalFrequency: OccasionalFord Transit CourierBrake pipe fitting touching the fuel tankA brake fluid leak may show up as a softer pedal or reduced braking performance; the source describes no prior symptoms.
Source for the symptom in the Ford Transit Courier^[9]
- High severityOccasionalFrequency: OccasionalLexus IS IIBrake fluid leak from the master cylinder rear seal (IS 250 and IS 220d)Brake fluid leak which, as the level drops, lights the low brake fluid level warning on the dashboard.
Source for the symptom in the Lexus IS II^[10]
- High severityOccasionalFrequency: OccasionalVolkswagen Caddy VFluid leak from the Caddy's rear left brake hoseSlow loss of brake fluid at the hose connection.
Source for the symptom in the Volkswagen Caddy V^[11]
- High severityOccasionalFrequency: OccasionalVolvo S40 IFront brake calipers on the 2000 Volvo S40 made of the wrong material that may crack and leak fluidBrake fluid leaking from a cracked front caliper, which according to the source can happen under heavy braking stress.
Source for the symptom in the Volvo S40 I^[12]
- Critical severityRareFrequency: RareCitroën C4 CactusBrake hose failure from rubbing against the shock absorber (built July-September 2019)Brake fluid may drip near the front shock absorber, with a resulting drop in the reservoir level and a possible loss of braking effectiveness.
Source for the symptom in the Citroën C4 Cactus^[13]
- Critical severityRareFrequency: RareToyota Yaris IIIBrake fluid leak at the rear brakesA brake fluid leak may appear around one or both rear wheels, with the brake pedal losing firmness.
Source for the symptom in the Toyota Yaris III^[14]

Brake fluid leak by brand

Other symptoms: leaks

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.Fiabilité Audi A4 (2001-2007)fiches-auto.fr · Reliability study · consulted 27 September 2026 · in French
2.C4 III, C4X Voiture particulière (fiche de rappel SR/02103/25)Rappel Conso (Gobierno de Francia) · Safety Gate UE · Official body · published 13 June 2025 · consulted 5 October 2026 · in French
3.Fiabilité DS3 Crossback (2019) : pannes et rappelsfiches-auto.fr · Technical documentation · consulted 27 September 2026 · in French
4.Ford Ranger Raptor (2019): brake hoses recall (Safety Gate A12/1952/19)car-recalls.eu · Other source · published 14 December 2019 · consulted 5 October 2026
5.Mercedes Citan W415 – Bekannte Probleme & Schwachstellengebrauchtwagenberater.de · Motoring press · published 30 May 2023 · consulted 5 October 2026 · in German
6.Mercedes-Benz Sprinter (2017 – 2020): front brake hosescar-recalls.eu · Other source · published 15 May 2020 · consulted 5 October 2026
7.Recall: Mercedes-Benz V-Class/Vito (2018 - 2019) brakes, firecar-recalls.eu (reproduce la alerta A12/1375/19 de Safety Gate) · Other source · published 19 September 2019 · consulted 5 October 2026
8.Toyota Celica – Brake fluid may leak (R/2004/168)car-recalls.co.uk · Other source · published 25 April 2005 · consulted 5 October 2026
9.Rückruf für Ford Tourneo/Transit Courier: Brandgefahr am Kleintransporterauto motor und sport · General press · published 9 July 2026 · consulted 5 October 2026 · in German
10.DVSA – base de llamadas a revisiónDVSA (Reino Unido), vía check-vehicle-recalls.service.gov.uk · Other source · consulted 5 October 2026
11.Volkswagen Caddy (2024): recall by brake linecar-recalls.eu · Other source · published 24 January 2025 · consulted 4 October 2026
12.Volvo Car V40 – Brake caliper concern (recall DVSA R/1999/100; S40, V40)car-recalls.co.uk (DVSA, Reino Unido) · Other source · published 18 November 1999 · consulted 5 October 2026
13.Fiabilité Citroën C4 Cactus (2014-2020) : pannes et rappelsfiches-auto.fr · Technical documentation · consulted 27 September 2026 · in French
14.Toyota Yaris (2013): fuga de líquido de frenos traserosCar-recalls.eu · Other source · published August 2013 · consulted 27 September 2026