A Lancaster woman is counting the cost of the theft which has become all too common in the Lancaster and Morecambe area.
Pauline Kent said she left her car in Edward Street car park on January 16 while she spent the day shopping in town.
When she returned to her vehicle, a Kia Sportage which she had owned for less than a year, she started it up and it made a loud bang.
"I immediate knew it was something to do with the exhaust," she said.
"I took it to the garage and they could see that the catalytic converter had been sawn off.
"In the end it cost £1,200 to get it fixed, however if I had done it through Kia, it would have cost £3,600.
"The exhaust pipe had to be replaced, and they also damaged the fuel pipe, and the DPS pressure sensor."
She said the council run car park in Edward does have CCTV, but the space she had parked in was obscured from the cameras.
Pauline said her insurance premiums would now go up because of the claim she has had to make to get the parts replaced.
"I'm extremely frustrated," she said.
"There's very little you can do about it. "
More and more people are reporting thefts of catalytic converters, which clean up harmful gases before they exit the exhaust pipe.
They contain precious metals, that can be sold on by thieves.
A catalytic converter is located in a box on the exhaust pipe under a car. In order to steal it, thieves slide under the car and use high-powered cutting tools to detach the box from the pipes around it.
Often, this results in other parts of the car being damaged.
This type of theft has been described as an 'epidemic', with a big rise in reported thefts in the Lancaster and Morecambe area over the last year.