Hello Jag friends. Some direction please. I got the Cruise Not Available (CNA) issue like a lot of folks. I replaced the usual culprits I learned about through this forum. For example: new ribbed PCV valve, new IMT o-rings, new battery, cleaned ground cable bolt, new plugs, new coils, new upper intake gaskets, new #67 fuse, tested and found no vacuum leaks. I clear the codes but within 5 minutes the CNA light returns along with the reduced performance issues and the code P0356 (occasionally but rarely others like P1000, P1314, P1316, P0306). So my fixes showed little to no improvement but no worries. At 111k the car was due for this maintenance anyway.

Now when I bought the car and my mechanic look it over, he said that there was evidence that it had a slow coolant leak. I wondered if that could be the problem somehow. So early this morning I checked the coolant. It was very low, although the car never gave me an indication that it was running hot (on the contrary all systems were normal) and the heater worked fine. Wow! I topped up the coolant and I was able to drive 45 minutes before the CNA light came back.

Could the slow leak of coolant have something to do with the CNA warning? Thanks in advance for your thoughts.

 

The signal from the sensor may block the cruise from operating. Rectify the leak first and then try again.

 

From codes it seems like something is wrong with cylinder #6.
Coil, Spark plug, wiring, power(+ground), or ECU malfunction.
Cylinder 6 is in the front bank, fortunately.

 

Good chance that Cyl 6 coil pack is breaking down by the look of the codes, you are getting misfires on No 6, it is very unlikely the coolant leak will cause CNA to come on unless its leaking on something else that then causes the misfire on 6

Aftermarket cheaper coils can cause issues, Denso or Delphi coils really should be fitted, spoke to a Jag specialist the other day re a problem I was getting and he had had a car in with new Lucas coils which are made in China, and these were causing the problem.

Try swapping coil packs from 6 to 4 and see if the codes 356 and 306 change to 354 and 304, this would def show coil pack problem.

Misfires will set Cruise Not Available warning, I have just danced this dance with mine, so this may be more typical than we think.

 

Thank you TilleyJohn. That was exactly it. I had my mechanic test it yesterday (yes, I'm try to be a diy guy, but I had to call in the pros). I was a little irritated because I put in the 6 new coils myself only a year ago. They were the quality coils too. But alas I suppose No one can build a perfect coil 100% of the time. So CEL is gone, Cruise Not Available is gone. I have a proud and able cat once again. Thanks for the affirmation.