2004 S-type - is the undertray necessary?
 

My 2004 S-type 4.2 is missing the undertray that covers the bottom of the car.

From what I understand this part was not on earlier models and some consider it a nuisance for maintenance.

The car does sit pretty low to the ground (compared to my 4X4 Ford Excursion!).

Should I be in a hurry to replace this part?

Thanks for the info!

It probably alters air flow and perhaps reduces water splash etc (and you do NOT want any moisture in those sensitive electronics!). You may get an undertray from a wreck :)

You don't want to be driving over anything that can hit the bottom of the car (whether you have an undertray or not)!!

No vehicle's undertray is really "necessary", but some vehicles benefit from them more than others do. Because of the complicated and very quirky electronics in the S-Type, you really don't want ANY moisture getting into your engine bay (search this forum using "throttle body" or "limp home mode" as key phrases and you'll quickly learn why). The undertray helps to prevent water splashes up into the engine bay and for that reason alone, it's worth the hassle factor of keeping it on the car. I hate having to remove it and then re-install it whenever I do routine maintenance, but it is staying on our S-Type for as long as we own it....

Most of the electronics can handle a splash or two. The only real reason (IMO) to have the tray on is to avoid water getting on the belts and making them slip. The power steering pump is the one you'll notice the most. When you drive over a puddle you'll feel the steering get stiff for a moment and that's the belt slipping on the p/s pulley. I haven't had a belly pan on my car for about 5 months and it really is unnoticeable. I just hate removing it every time I go under there.

Underbody Tray
 

The underbody tray is for aerodynamics that helps with noise and a slight fuel mileage improvement. You don't need it but might have more road noise, especially at highway speeds and above. I don't find it much of a pain when servicing my 2005 STR. Once I took it off and on a couple of times it's pretty quick now. I think you need to look at it like this. The Jaguar is a high end and very complicated car regardless if it's an STR or a 6 cylinder diesel so why not have all the things Jaguar put into the car at the time of manufacture?
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thanks for the info!
 

Thanks a lot, all! I think I will put it on the list to get.

-Brice

Just one more thing on this topic. There are a lot of lines that run pretty low and would be exposed to damage without the tray (the one that gets in my way when I change the oil filter comes to mind). I'm sure they considered the tray being there when they layed out the design. Just food for thought.

I can understand that. I am going to keep mine on because my engine bay looks pretty darned good for a 6 year old car. I think that most of that
is due to having that belly pan.

I just had mine replaced. When I got an oil change they said it was broken and they used a zip tie to secure it. I needed to get the windshield washer pump replaced by the dealer so I had them replace the undebody tray. Not cheap, but nothing is on a Jag. When I bought my used Jag I didn't factor in the fact that repairs are so costly! Thankfully, I've not had many problems and ones I have had are usually covered by the extended warranty I bought.