My 2007 FFRR Supercharged has a 'Reduced Engine Performance' warning and engine management light permanently on. Restarting the car or leaving it overnight does not reset it. We've done a couple of trips on the autobahn this year and both times at speeds of about 90/95mph the warning came on (message not light) and the power was greatly reduced. I didn't get this looked into as it would reset when the car was restarted and at that speed not a problem for 99.9% of its use in the UK.

This week the message came on after driving the car with the transmission in sport and after accelerating reasonably hard. It is now permanently on. At the time there was no lack of power and there continues not to be with the car driving fine.

Wondering if this might be the issue with the sc coolant pump being wired wrongly as I have read about on here, but I'm not sure of the symptoms are the same.

I've got some spare time on Saturday and I don't mind basic spannering, does anybody have some DIY guides for things I can check? I haven't been able to find any on here, but it's possible I'm not looking in the right place?

Any opinion or advice much appreciated!

Here's a nice pic parked outside the Ritz........

Have you tried cleaning your air filter sensors?

No, I'm a newbie when it comes to maintenance on this car, usually I'm too busy and it goes to my local LR indy. Have some spare time on Sat and trying to save some money if I can.

Are the sensors easy to get to and clean?

Hi, Not sure of the layout of your car but on mine which is 2011 4.4 take the EGR sensor off the air filter you will have to buy a can of EGR cleaner (spray) give a spray wait to dry and replace carefully as not to disturb any dust in the air box?
Worth ago?

It's a S/c Tinman so I don't believe they have any EGR bits. Them's for oil burners.

Bazzer, I suspect your problem is the supercharger coolant pump. They all go tits up eventually and it needs changing and the wiring sorting out. Incorrectly wired plug from new that makes the pump run backwards and it dies around 70k miles.

Get it into your local indy and they'll sort it for a couple of hundred including parts.

Mine had the additinal problem of blowing fuse 7 in the boot, every time you switched on the ignition and my guys put in a new wire from back to front. All sorted after that. 2017 5.0 Autobiography Supercharged
2005 Merc SL350
2005 Disco HSE 2.7 oil burner