Fire engines surrounded the aircraft after it landed safely at John Lennon Airport this afternoon
The easyJet flight returned to Liverpool shortly after take-off, with officials confirming the defect.
The aircraft was headed to Paris when the pilot radioed air traffic control and declared an emergency.
Fire crews assembled on the runway, before the aircraft landed safely around 20 minutes later.
A spokesman for the airline said the decision to return to Liverpool was purely a 'precaution.'
Eyewitnesses said the twin-engine Airbus A320 'sounded bad' as it came into land.
Others also suggested the planes doors were open, but this was denied by both easyJet and the airport.
Passenger Jan Nethercote told how it was around 20 minutes into the flight to the French capital when the announcement was made.
'They told us a minor fault had happened with one of the engines and they were taking us back to Liverpool,' she told the Liverpool Echo.
'It was explained to us later the fault happened at take off but they made the decision to continue.
'However it developed into something more serious and in the end it looks like they lost the use of an engine.'
Jan, who was going to Paris for a long weekend, added: 'Everyone on the plane was very calm considering, because the crew and the captain were so good.
'It was a little bit scary though when we were coming in to land and saw fire engines with their lights flashing lined up on both sides of the runway.
'You thought 'Are we going to go on fire?' which was worrying.
'When we landed on a far away part of the airport, everyone applauded, and then the engines were shut down quickly. The plane was then towed in.'
Jan said the flight, which usually has around 180 passengers, looked completely full.
Several people on the ground tweeted to say they could hear strange noises coming from the plane on take-off.
Barry Jenkins tweeted: 'It went right over me, genuinely thought it was coming down, never heard noise like that in my life, like metal grinding.'
The plane was thought to have dumped fuel over the sea after changing course over Cheshire.
A spokesman for easyJet said: 'We can confirm that flight EZY 7045 from Liverpool to Charles de Gaulle on 19 June returned to Liverpool shortly after take-off.
'The Captain took the decision as a precaution due to an electrical fault.
'The flight landed safely and passengers disembarked as normal and will continue their journey on a replacement aircraft.
'The safety and well-being of our passengers and crew is always easyJet's highest priority. We would like to thank passengers for their patience and apologise for any inconvenience caused.
'The engines remained fully operational.'
A spokesman for John Lennon Airport said: 'The easyJet flight from Liverpool to Paris left just before 1pm.
'The pilot declared a full emergency and requested to come back to Liverpool.
'Emergency services responded in line with standard procedure.
'The plane landed perfectly normally and passengers disembarked in a normal fashion.'
The way things are going with mankind's technology, we may end up regressing back to such modes of travel as foot, horse, or sail-power.
Our modern world seems to be falling apart far faster than even it's in-built obsolescence was designed to achieve.