hi I have a 2.5l s type with restricted performance, the engine light is on but the car keeps coming out of restricted mode engine light stays on & the car drives as usual. I have taken the car to a garage they hooked it into a laptop & no fault was found. has anyone else had this problem? does anyone know how to cure the problem?

If the ecu light is illuminated then there must be a code stored. I have known some code readers to not find codes where others have so it's possible that the garage is using a 'cheaper' or less capable reader (unless you took it to a Jaguar garage?)

The only component I've come across in my 35 years experience which has caused exactly those symptoms, and on occasion hadn't caused the ecu light to illuminate so no fault code, is the MAF sensor, or Mass Air Flow sensor.

The only way to find out though is to replace it with a known working part.

Other parts I would consider would be the cam position sensor, fuel pressure regulator, accelerator pedal potentiometer, lambda sensors (although these don't generally cause power loss). There are a few others but they aren't what I would consider the main culprit.

All of these would cause an illuminated ecu light but as there is doubt over the code reader, I would still consider them

Welcome to the Club, Jon.

 

As you have found out already, there are some very helpful and knowledgeable members in the Club.

 

Regards,

 

Peter.