A section of the wiring is damaged, rubbing on something, or not properly clipped up. Note that the circuit can still be working perfectly — it's the condition and security that's being assessed, not the function.
Wording as it commonly appears on an MOT certificate: “Electrical wiring damaged, chafing or insecure”.
What does it mean?
A section of the wiring is damaged, rubbing on something, or not properly clipped up. Note that the circuit can still be working perfectly — it's the condition and security that's being assessed, not the function.
How serious is it?
Usually recorded as: Minor, Major. The tester assesses the actual vehicle on the day, so your certificate is what counts.
What normally causes it?
- Cable ties or clips that have perished, letting the loom drop onto a moving or hot part
- Chafing where a loom passes through a bulkhead grommet that's gone missing
- Rodent damage, which is more common than people expect on cars parked up for a while
- Poor previous work — towbar wiring, alarms and stereos are the usual offenders
What a mechanic would check
Follow the loom from end to end and look at every point where it touches something else. Anywhere the insulation is shiny or worn through gets repaired properly with heatshrink and re-secured — not wrapped in tape and left.
What might need replacing
- Wiring repair and re-securing
- Grommets, clips and cable ties
- A section of loom replaced where damage is extensive
Can you still drive it?
Recorded as Minor or Major depending on severity and location. Chafed wiring near hot or moving parts is a fire and short-circuit risk, so it's worth doing properly rather than patching.
Repair cost
Usually labour rather than parts. Cost depends entirely on access and how much of the loom is affected.
Before the retest
Battery, wiring and horn faults are usually quick to fix but easy to forget about. Make sure the battery is clamped down so it cannot move, the terminals are tight and there is no fluid leaking. Check that no wiring hangs loose or rubs on moving parts, and that the horn gives a steady, continuous note.
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 electrical 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.