Fuel is escaping from somewhere in the system — a pipe, union, tank, filter housing or injector seal. Even a weep is treated seriously, because fuel and hot exhaust components in the same area is exactly how car fires start.
Wording as it commonly appears on an MOT certificate: “Fuel system leaking”.
What does it mean?
Fuel is escaping from somewhere in the system — a pipe, union, tank, filter housing or injector seal. Even a weep is treated seriously, because fuel and hot exhaust components in the same area is exactly how car fires start.
How serious is it?
Usually recorded as: Major, Dangerous. The tester assesses the actual vehicle on the day, so your certificate is what counts.
What normally causes it?
- Perished rubber fuel hoses on an older car
- A corroded fuel pipe or tank seam
- A leaking injector seal on a diesel, which shows up as a black tarry deposit around the injector
- A missing or non-sealing fuel cap
What a mechanic would check
Find the actual source rather than the puddle, since fuel runs before it drips. Clean the suspect area, run the engine, and look again — that's the reliable way to identify a weeping union or seal.
What might need replacing
- Fuel hoses or a pipe section
- Injector seals or washers
- A fuel cap
- Tank or filter housing repair in worse cases
Can you still drive it?
This can be recorded as Dangerous, and if you can smell fuel you should not drive the car. Get it recovered or repaired where it sits — this is genuinely a fire risk, not a formality.
Repair cost
A fuel cap or a short length of hose is minor. Tank or injector work is much more involved. Get the source properly identified before pricing.
Before the retest
Re-check the specific item on your certificate yourself before the retest — catches that latch first time, no fuel smell or drips under the car, doors that open from inside and out. Most of these are inexpensive repairs, so it is worth also looking over any advisories on the certificate while the car is booked in, rather than waiting for them to become failures next year.
Retest rules
If the vehicle stays at the test centre for repair and is retested within 10 working days, a partial retest is often free; some items qualify for a free retest if you bring the car back by the end of the next working day. The exact conditions are set out on GOV.UK, so confirm with the test centre before you leave. A major or dangerous failure means the car cannot legally be driven away unless the previous MOT is still valid and nothing dangerous was recorded — check your certificate first.
Related help
More other mot items failures · MOT failure decoder · Ask a mechanic about your certificate
This is general guidance from a UK mechanic, not a substitute for a physical inspection. Only the tester who inspected your vehicle can confirm what was recorded and why.