2007 XJ8R
Check engine light is ON
"VEHICLE TOO LOW" is also annunciated on the dash.

When in PARK or NEUTRAL a motor of some sort is cycling on and off
about every minute or so. The motor will shut off if trans is shifted
into DRIVE or REV, or brake pedal applied. The motor noise appears
to be coming from the left/front area of the engine bay just under where
the air filter is.

Is this the air suspension motor/pump? (I thought that was back in the
trunk under the spare tire(??))

Any help appreciated...

Thanks!

 

Well that should be your compressor for the airsuspension in front of the left front tyre hiding behind wheel well and bumper. If it is starting like every minute wich is not a good sign nor is it normal.

 

COMPRESSOR( Wabco) is FRONT LEFT
AIR reservoir 5liter and valveblock sending air to airsuspension struts are both below spare wheel in the boot.
6mm color coded nylon lines are going from there to the front struts, 4mm color coded nylon hoses are going to the rear struts . From the compressor in the front there is one 4mm nylon hose going to valve block the 6mm to reservoir
wabco module is behind there rear back seat.
compressor delivers about 14 bar of pressure or should , sends it to valve block and is being send from there to the struts or either to the tank
there are new piston rings and seals available for the compressor like 25€£$ bagpipingandy compressor referb kit.
normally the compressor starts 20 seconds after engine start and runs for about a minute even when driving. If not enough pressure build up in about that time is reached you will have an orange light on the dash. If tyres are at about a finger distance to the wheel well you can drive , and at about 25mph the compressor will start again for about a minute trying to reach the goal.

 

I would agree the issue is compressor keeps cycling to ensure the correct amount of air is sent to all four struts.
- Now you may want to have each strut/shock check for proper operation.
- I recently had to replace my rear Arrott's Struts because I also had Vehicle too low warning and my rear left side strut appeared to be the culprit.
- Replace both ,,, no more warning lights and the vehicle sets even.
- 110K miles - First shock replacement.

Melvin
2004 XJR

 

Without codes your operating blind. The air system is complex and has many parts. I have worked a lot on this and you need to get a working SDD to properly troubleshoot where your problems are. Loading the parts cannon is expensive and most likely won't work.

Also be aware that it's very common to dump the expensive failure prone air system and install coil springs.
So think about how much money your willing to spend on the air system and compare that to the coil spring conversion cost.

Another factor is can you DIY anything? You have not said if you can or not?
Because paying to get this repaired can easily run into thousands of dollars. Also Jaguar has abandoned it's customers so any car 10 or more years old will most likely be declined by a Jaguar dealer.

Any chance you have an independent garage that you can trust?
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Failing sensor(s), vacuum leak.,.. 'etc.'

Nowt to do with the air suspension. Chase that separately, but Real Soon, Now. It is actually the more worrisome and potentially more costly than the suspension if not caught and fixed right away. Decent scan tool is essential. iCarsoft LR V3 serves me well for both the XJ8-L and the Rover L320. They have competition.
Also with amber LED but that one is NOT the CEL LED?

Leak in the air suspension system. Most often at the top of one or more air struts, worsening as weather goeth colder. These leaks can degrade slowly enough to defer hard fail for five to ten years, so it has probably been getting ready to screw your budget for 'a while, already'.

That's the WABCO (formerly Westinghouse Air Brake Company) air compressor.
The leak will eventually wear it out.

Not to worry:

New WABCO is not terribly dear. Mercedes & BMW plus a few other luxo cars used the same WABCO, plumbing, and Bilstein Air Struts. Most of them, JLR included, have factories in China, and source those parts from China at least part of the time. Shop carefully, costs are reasonable.

Rebuild is a good idea. Even if you (also) buy a new one. "Bagpiping Andy" makes an (improved) piston/seal kit. Well worth it. Not hard to do. Don't forget to renew the Silica Gel dessicant beads. I also ordered a new mounting kit, as the rubber goods were degrading. Quieter that way.

Failing struts:

After long research - most of it right HERE in-forum, I took a dual path:

Plan B first: I bought a full set for all four corners of 'coilover' passive/all-mechanical struts. MaxPee DingRods. 'Adjustable'. Under $300 at the time for all four. Still in the box they arrived in. Still my 'fall-back' if Plan A failed or fails in future.

Plan A aftermarket air struts. First was a pair for front: They generally fail first, and had done. When the non-OEM air struts worked well, I added a pair for the rear. I selected "Strutmasters" Chinese-made air struts. I suspect these are the same as Suncore.

CAVEAT: These do not have the electric shock MODULATION solenoid for the CAT/ ECATS part of the system.
BFD. Neither do Coilovers.

OTOH open air, bare driveway, the proper wrenches, two jacks and a tire-demount pry bar, an impaired Octegenarian can swap and calibrate in about one wall-clock hour, each corner.

Healthier hand one hour each end.

Expert, with a proper hoist, 30 minutes to one hour, all four corners?

Follow the Bilstein You Tube video instructions, one method, one video per each end of the car. Only 'calibration' required is a tape measure, metric or do the math.

Best to do front pair together, rear pair together, but one at a time with several weeks if not months or years in-between CAN work, too.

It just isn't that hard.


Afterwards: Bend leads of four-each ~15 Ohm 10W 'sanded' wire-wound resistors so the leads fit the OEM electrical connector at each corner where it no longer has a home on the Chinese air struts. Tape and/or tie-wrap in-place and the amber LED and 'CATS System Fault' warnings go away, for good.

Valve block servicing, Voss fitting O-ring replacement, or tubing leaks are not black magic, either. Covered right here in-forum.

Performance:

I cannot even detect the absence of the CATS modulation.
OTOH, I am no longer pushing the vehicle to 11 Appalachian tenths on bad 1 3/4 lane West By God Virginia blacktop, either.