I have owned several Porsches for more than 10 years and have always properly maintained them with dedicated Porsche garages and warranties.

On renewing the warranty for my current Boxster I was told by Porsche Mid-Sussex that the car had been driven over the limits set by Porsche and that the car could no longer be covered by the Porsche warranty. It was explained that the car’s computer had recorded engine rpm readings in excess of 8900 rpm on two occasions at 1091.7 hours, and on three occasions in excess of 8400 rpm at 950 hours.

The only explanation given was that it occurs when the engine is mechanically over revved by shifting into a lower gear at very high speed and mechanically exceeding the rev-limiter. I queried this because there is no way I could have driven the car in this manner.

I am a lady driver in my 50’s and drive carefully and within the law of the country. To date I have no speeding fines or endorsements of any kind -testimony of my driving style. Porsche Mid Sussex are adamant that their computer readings are 100% reliable and suggested that someone else must have driven the car in this manner.

This is not possible as I am the only the driver of the car. Only Porsche garage staff have access to the car when it is for a service.

The number of similar readings for other Porsche owners in the UK is alarmingly worrying and appears to be a fairly recent phenomena. In setting these parameters and given the serious and significant implications of an automatic warranty denial, Porsche have a responsibility to investigate these occurrences and provide a proper explanation.

Two revolutions at 8900 rpm correspond to a small number of milliseconds of time. Computers are not 100% fail safe and it is quite possible that these are false readings caused by a technical glitch and should be ignored. I know I could not have driven my car in the manner required for the computer’s reading to be correct.

Do you have any advice on how best to approach Porsche in Stuttgart regarding the fact that the only explanation can be that a faulty ECU has assigned non-existent over-rev occurrences to the log.

Do you know of any other possible explanation for these readings?
Would you advise I demand a replacement ECU?

The report for my car shows only the engine hours when the over-rev occurrences were logged. The date and mileage data of these occurrences would provide more useful information but Porsche claim these were not available and that the log cannot be re-run. Are both these claims true?

I look forward to hearing from you and thank you for any advice you can give me.