XJ40 - Fuel injection ECU location

Can someone please tell me where the fuel injection ECU is located?

Thank you!

Kind regards,
Bard Thomas

ECU is located under passenger side dash

Adjacent to the footwell fusebox, 2 large harnesses will be plugged into it. Press one side of each plug to release and remove by swinging plug out.

The plugs are “hooked” from one side.

Thank you for your specific directions! Under the dash is a bit “general direction”-ish.


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I am not sure about the vehicles that are Left hand drive, I am in Australia and we are right hand drive, and I found it fairly easy to get to on mine, remove the battery carrier, (4 bolts.) then you will come accross the vaccuum tank, ( a small plastic tank.) it should just lift out. Then that is where I found the cover in which my unit was mounted. (I found it completely by accident.) removing all the wiring from the car in an effort to restore it all. Aaaand to modify a few things as well.

Hi Clive,

After following the previous directions and NOT finding the ECU (fuel injection), I hope your tip is valid because I was getting rather discouraged… It does make sense, too, so I’ll give it a go tomorrow!

So, on this LHD car, it would be on the right side of the engine bay, beneath the battery.


I could only guess that to be the case, I only found it because I am stripping the car down to nothing for a total rebuild and paint, and I took all of my stuff out from the top, there is a tray at the bottom, that maybe, but I think there is a heater fan in the way.

This picture is probably the best way I can say where things are, like I said I am guessing it will be a reverse picture to mine because it is RHD.

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As you can see I am actually going way past the point you are needing, I decided to answer you because I too had trouble finding the same thing when I first got my cars.

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What is the VIN/year of your LHD car? What country/market is the car from?

Most people add this info to their ID card so specific advice can be given.

I have a US/CANADA '94 and can assure you the ECU is where I described.

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not sure if this helps but this is my 89 over passenger knees.

I would be good to update your forum information with your location and car model and year being referred to. On my LHD 1990 4.0 XJ6 (XJ40) the engine management ECU is on the RH side behind the knee bolster.

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Clive …

I thought I had really dug apart my '89 XJ40 to remove the evaporator housing but looking at the picture of your excavation you have truly gone where few owners have ever gone before … WOW !

Yes I have dug into it a little, this car has been in a shed for 12 years and the whole heater/climate control box has been home for a few rat’s for quite some time, so for me I am replacing what I can and rebuilding what I can’t buy. anyway I am getting a lot of information about my car as I shuffle my way through the posts of others, this site has been very helpful even when I have not post any reply.