A few months back my 2004 Xtype 3.0 engine light came on and the engine started chugging. it appeared to happen about the time when it wants to shift. So I went and had it scanned and it came up O2 sensors. so I replaced them (ugh) and the chugging still is happening and the Code that it is saying is still O2 ... What sensor or part is before the O2 sensor that may be erroring this out? What questions or answers can I ask or provide so I can get this resolved and fixed as I want to sell the car but if I let people test drive this way I will have forever. Thanks a MILLION

SOURCE: 2004 Jaguar x type electric radiator fans not operating

check out with your dealer as you might have a recall to fix this problem.
XT303-S932
X-TYPE
DATE 01/03
MODEL
2002-03 MY
X-TYPE
VIN
C00294-C91719
Overheating - Cooling Fans Inoperative - Replace Module Prior To Retailing - Service Action S932
This Service Action Applies to Vehicles That Have Not Been Retailed
Issue:
The cooling fan module on X-TYPE vehicles may fail under certain circumstances. There are various root causes but the design and quality of the printed circuit board within the cooling fan module are the most significant. The NAND gate used in the circuit is detective causing multiple failure modes, this can result in high engine temperature and overheating due to the cooling fans not operating.
A change has been implemented in production from VIN C91720. On these vehicles a 'Philips' printed circuit board has been used that has a modified voltage spike protection strategy.
Action:
To prevent customers from experiencing this issue, install the latest specification cooling fan module on 2002-03 MY X-TYPE vehicles within the above VIN range that have not been retailed.
PROCEDURE
1. Install new cooling fan module (see Workshop Manual, JTIS CD ROM, section: 303-03, SRO 26.25.38).
Parts Information
Warranty Information:
Warranty claims should be submitted quoting S932 in place of the warranty fault code together with SRO: 26.25.38 and the relevant part number. This will result in a labor time allowance of 0.8 hours to replace the cooling fan module and payment for the part used. Should the vehicle be brought back into the workshop for this action alone to be undertaken, an additional labor time allowance of 0.1 hours can be claimed quoting SRO: 10.10.10 for drive in/drive out.
Warranty claims should be submitted quoting the information found in the table. This will result in payment of the stated time and, where applicable, parts/miscellaneous expense codes.
The options that allow for drive in/drive out may only be claimed when the vehicle has been brought in to the workshop for this action alone to be undertaken.
The SROs and parts items listed above have been included for information only, there will be no requirement to enter the parts or SROs onto the claim.
NOTE: Always perform a DDW claim search first to determine whether this service action has been performed on this vehicle. The warranty selection under the vehicle inquiry will give a listing of all claims against the vehicle. If this service action number appears in the program code field, do not perform this service action.

SOURCE: 98 jaguar xj8 won't start

Ten is not a problem persay but is it a traffic light to light ten miles? never really hittin any highway? If so ive seen lots of plug fouling from short trip situations like that. nothing wrong with car mechanically at all--just the way v8's are. They need taken out and run hard every couple months. Pretend your in the cannonball run--less your area is like mine and crawling with police :) Thanks hope I helped.

SOURCE: P0420 Error code, I had the sparks plugs replaced in dec...now one is misfiring again.

i dont know if this 402 code is a miss code on a jag but usually miss codes are p0300 codes. if you are hearing a ticking and you own a spray bottle, an old mechanics trick is to mist water on the plug wires while the engine is running preferrably in the dark.

SOURCE: Jaguar x type 2004 2.5 petrol V6, 38500 miles, codes P0171, P0174

Have exactly the same issue on 04 jag x type 2.5. So far have replaced fuel filter, air filter k&n, plugs ngk. Codes cleared, same issue. Seems to appear when air temp is cold and eng is warm.
Am replacing upstream O2 sensors and cleaning MAF next. Will keep you posted if it clears up. Did you ever find the cause?

SOURCE: 2000 Jag S Type Help!

fail safe mode is something the vehicle computor will go into when there is a problem with the vehicle it allows u to get off the highway or road safely you need to take vehicle to repair shop or your dealer which ever u prefer Failsafe engine mode on a 2000 jaguar s type is caused by a stopped up throttle body. Jaguar says not to clean the throttle body since it has a protective coating to help keep deposits from accumulating. You can clean the throttle body as long as you use ONLY throttle body cleaner that states it is safe to use with a protective coating. The butterfly valve in the throttle body will actually stick not allowing air to flow into the manifold causing failsafe engine mode to kick in reducing the amount of power your engine will produce. To solve the issue just clean out your throttle body, it will cost you around $5 dollars and take 1 hour of your time.

This is from wikipedia.