Garages in the town yesterday told the Chronicle & Echo they had dealt with about 30 unhappy motorists whose cars had to be drained of what they believed to be contaminated petrol.
Trading standards officers across the region have now launched an investigation into claims the petrol had been contaminated with ethanol, causing vehicles to judder, misfire and lose power.
Bill Gunn, general manager at Gerald White Group at Kislingbury, said two drivers had approached his garage with problems appearing to be caused by fuel contamination. Both had used pumps at the Tesco garage in Weston Favell.
Mr Gunn said: "The work might well cost in excess of £1,000. I sympathise with the drivers as they should be getting the quality petrol they deserve from stations."
The RAC said the problems – reported across the south-east of England – seemed to be particularly affecting the oxygen sensors in vehicles. These are attached to the exhaust and determine the mix of oxygen and petrol supplied to the engine.
Independent oil company Greenergy said it was testing fuel supplied to Tesco and Morrisons supermarkets to see if it was faulty.
Greenergy, which supplies "greener" fuels, said its "extensive" tests on the batch of fuel showed that it met industry standards, but it was continuing its investigation.
A spokeswoman said the fuel contained up to five per cent bio-ethanol, which was within permitted limits.
The company added in a statement: "Greenergy has been made aware that some drivers using our fuels are experiencing some problems. We take this very seriously."
Trading standards said its officials were also testing a number of samples but had not yet had the results.
Ian Hillier, a petroleum spokesman for the Trading Standards Institute, said: "I understand there have been around 75 to 100 complaints from people in south-east England.
"Including ethanol in petrol is not really contaminating it, but there has to be a clear warning to people who buy petrol as to exactly what is in it."
The penalty for supplying fuel which does not meet industry standards is a £5,000 fine.
A member of staff from Evans Halshaw Citroen dealer, in Wellingborough Road, Northampton, said around 11 drivers had taken their cars in. Some had filled up at Tesco, although at least one had been to a different petrol station.
He said: "It's apparently all over the south of England too.
"The petrol seems to have got some kind of contamination. It means the car misfires and in some cars it will bring an engine management light on.
"But it's not the company's fault; they bought it in good faith and anything could have happened at the refinery, you just don't know.
"I feel sorry for the drivers because they were only doing what anybody else would do; buying fuel."
A member of staff from Camden Renault on the Riverside Retail Park said: "I know we have had an influx of vehicles, but the reason for that is not known.
"We have had about nine vehicles in with associated problems. Renault UK is looking at the problem and it's mainly based in the south."
A spokesman from Northamptonshire County Council Trading Standards department said: "We have received three complaints from Northamptonshire residents and will be following these up to investigate further.
"Anyone with any concerns can contact Trading Standards by telephoning Consumer Direct on 08454 040506."


Have YOU had any fuel problems? Let us know by contacting our transport reporter Emma Rees on 01604 467034 or email: emma.rees@northantsnews.co.uk.

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