Police are urging car fanatics to check their vehicles after two young people died of carbon monoxide poisoning in a car that had been dangerously modified.

Nikki Willis, 23, of Fox Crescent, Chelmsford, and Thomas Putt, 20, of Wren Close, Leigh, were found inside a Ford Fiesta that had been altered by trainee engineer Tom himself.

During the investigation, forensic tests found the car was emitting levels of carbon monoxide that were 1,000 times that of a factory–standard vehicle when it was left idling with the pair inside on Monday December 5.

Police carried out forensic tests on Tom's car using CO probes

An inquest, held yesterday, heard how they were discovered in Tom's blue Ford Fiesta ST outside Nikki's home in Fox Crescent, Chelmsford, at around 10.30am.

Speaking after the inquest hearing, in which their deaths were ruled accidental, Detective Inspector Rob Kirby said: "It is fair to say there was a unique series of events that came together to led to this tragic incident to take place.

"The combination of the modifications, the cold, still weather and the engine running whilst the car was stationary, all contributed to what happened that night.

"Tom was not inexperienced, so even if you think you know what you are doing, this can still lead to unintended consequences.

CO levels in Tom's car were 1000 times higher than that of a factory model Ford Fiesta

"If you have carried out modifications on your vehicle, I urge you to satisfy yourself that these modifications are legal, and more importantly, safe, by consulting a qualified mechanic.

"Essex Police along with Tom and Nikki's families and Ford UK want to ensure a tragic event like this can never happen again. Please have your vehicle checked. "