I've had an amber EML and a frequent "Reduced Performance" error on my 2010 5.0 SC recently. The car was booked in for a different job to be done and I was able to not use it whilst waiting for it to go in. However, during that time I fitted a towbar, mainly so that the towbar coding could be done while it was in.

In order to connect the towbar electrics, as a precaution I disconnected the battery for a short time while I plugged the electrics in.

When I went to drive to the garage for repairs yesterday, I had a completely clear dash, but what's more annoying, they have plugged it in and said that there are no fault codes stored at all! Surely the codes are not wiped by a battery disconnect?? I though they were stored for x-number of ignition starts or something like that?

The errors are bound to recur as soon as I get the car back, which will mean another return visit. On the plus side I have just bought an IID tool so at least I'll be able to read them I guess. 5.0 S/C Autobiography
Defender 3.9i Auto, Aston Martin DB9, Fiat Coupe 20V Turbo Plus and seven, no eight, bikes!

Previously:

4.4 AJ V8 Vogue, RRC, 4.6 VSE P38, Disco V8, SIII V8 - there's a theme here! Plus multiple others, some of which were also V8s!

When does it drop into reduced performance, any particular thing you are doing..?? Pete

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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Nothing, it's completely random, and when it first started doing it there was no discernible drop in performance either - but then it seemed to get worse. I pulled away from some lights, not that hard, and it bonged and threw the Reduced Performance message and nearly stood on it's nose with the loss of power! That was when I stopped using it, it's now with a decent indie (AHL) but they can't read any faults from it. 5.0 S/C Autobiography
Defender 3.9i Auto, Aston Martin DB9, Fiat Coupe 20V Turbo Plus and seven, no eight, bikes!

Previously:

4.4 AJ V8 Vogue, RRC, 4.6 VSE P38, Disco V8, SIII V8 - there's a theme here! Plus multiple others, some of which were also V8s!

Mine started to do that but only when at full throttle (mostly), showed no codes and the reduced performance reset by restarting it... It did it numerous times before it left a fault code P0087 low fuel pressure...

The JLR workthrough was filter, pressure sensor and lift pump... all changed, still did it...

I hit the US Jaguar forums as they use this engine far more than we do and found four similar cases which were resolved by new mechanical fuel pumps

Mine is sat in pieces as we speak as I change the two high pressure mechanical fuel pumps,...

You can use the IID for real time values and monitor fuel pressure which should show a drop before it goes into reduced performance... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Mine sometimes bonged and said reduced performance but ran fine with no loss in power... I think your problem sounds similar to mine... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

It does indeed Haylands, thanks for this. If the garage don't/can't find it this week I'll have to monitor, knowing that the IID will pick up your symptoms is helpful to know. 5.0 S/C Autobiography
Defender 3.9i Auto, Aston Martin DB9, Fiat Coupe 20V Turbo Plus and seven, no eight, bikes!

Previously:

4.4 AJ V8 Vogue, RRC, 4.6 VSE P38, Disco V8, SIII V8 - there's a theme here! Plus multiple others, some of which were also V8s!