I have just bought a 2003 XK8 with 12,500 miles on it. It is like new and everything seemed to work well. I recently got a check engine light and I plugged in an Autel Smartscan 3000 to see what the codes were. It says that it is a PO442 fault and I have been told that usually means a bad gas cap. I ordered, and installed a new Jaguar XK8 gas cap but the fault seems to be still there. Any thoughts or ideas.

I tried erasing the DTC but it seems to "fail" at erasing but yet when I re-scan, it says no codes. The check engine light does not go out and then when I try it again the same PO442 fault appears. Some say that you have to drive it for a few days but this seems strange.

Thanks,

Scot

 

Hi,

P0442 is an engine evap fault. May not be the gas cap.

Check out this old thread.
https://www.jaguarforums.com/forum/x...p-leak-148738/

 

The standard answer for this evap code is to run a smoke test: you have to inject low pressure smoke in the evap system (there is usually a port with a green cap for this). The smoke will fill the system and show where the leak is. Chances are it will be some short hose or hard line with a crack. The purge valve may also need replacement if it is rusted shut or is leaking. Most shops can do a smoke test, you can buy a home smoke tester (check eBay/Amazon) or you can even make your own with an old soldering iron, a jar, hoses, baby oil and a bicycle pump.

Barring that, you can follow and check all the lines from the throttle body to the purge valve in the driver-side wheel well (behind the liner), and on under the car to the charcoal canisters, etc.

Separately, check the condition of the oil lines to the oil cooler. They are, arguably, the one flaw left in these 4.2L XK8/Rs. The rubber section can separate from the Aluminum tubes and dump all the engine oil out in seconds. You generally get a warning seepage at one or more of these interfaces, but at this age, all 4 need replacement if original. Easy job, but a bit expensive in parts. And yes, all 4 sections need to be replaced because they all see the same high oil pressure from the pump to the rest of the engine.

Best of luck, keep us posted.