Signs
Little or no acceleration, revs limited, the gearbox stuck in one gear, and usually a warning light.
Common causes
Turbo or boost faults, a clogged diesel particulate filter, sensor faults, misfires, fuel delivery problems or transmission faults.
Restarting
Switching off and restarting sometimes clears limp mode temporarily, but the fault is still stored and will return.
What to tell the mechanic
Make, model and fuel type, when it happens, any warning lights or messages, and any codes you have.
Safe to drive?
Drive gently to a safe place. Avoid motorways if you cannot keep up with traffic. If it came with overheating, oil pressure or smoke warnings, stop.
General guidance only, not a diagnosis. If in doubt, do not drive it and have it inspected. In an emergency, call 111.
Who can help
Get quotes for car diagnostics near you
Questions
Is it expensive?
It depends entirely on the cause. Proper diagnosis first avoids replacing parts that are not faulty.
What should I put in the job?
Symptoms, warning lights, fuel type and any recent work.