I bought the car recently at about 93K miles and it was showing codes for a bank two (right side) VVT problem.

I replaced the solenoid and the problem went away for a couple weeks, 200-300 miles, and lots of starts and stops. But now, it is back and returns very quickly if the code is rest or if the computer is reset.

So, what's up? Did I get a bad solenoid? I don't think so, it was a new Jag part and it worked well for an extended period. Also, the electronic signals to the plug are good and the solenoid tests OK in term of internal resistance.

One might guess that it is the unit at the end of the cam. If so, why did the new solenoid work for two weeks if it was not the fix?

 

Ie no broken wires....clean the connector

 

More than likely the VVT passages are clogged. (VVT system is managed by oil pressure)

Rarely does the solenoid go on these cars.

Try this:

Get engine flush - run car (from cold) at idle for 15 - 20 minutes - drain oil.

Install 5W30 oil, new oil filter and sub 1 quart oil with Mercon V trans fluid and drive as normal. Trans fluid is highly detergent and breaks down the oil gunk in those VVT passages over time. It may take a while to get the code to go away but in your case - it shouldn't be too long...

I have done this with success on my 00 S Type and I always put in a bit of Mercon V in the oil and drive a few hundred miles before the oil is due to be changed. The trans fluid makes a huge difference...

 

I will try the ATF added cleaning suggestion and give it time. I was initially in a hurry because I needed to register and smog test. Now, not such a rush.

I did confirm 12v to the solenoid and when I applied 12v to the solenoid pins, I did hear a click. I expected to hear something more substantial but it was just a click/tick sound. The resistance measured 9.8 so I'm guessing the solenoid is OK.

That said, I can't imagine why a new solenoid made the system work OK for a few hundred miles if it was a clogging issue.

 

Is your car a V6 or V8? If it is a V6 you may want to check your oil pressure with a gauge. You may have an issue with the main bearings. When the pressure is low the VVT will not work properly. You will not be the first person to have this problem.