Well, had the XKR serviced last week (routine interval, 4 yr). Couple of days later CEL came on. Secured OBDII reader to check it out and was MAF code. Next day light went out on its own.

Now today, was sitting in the garage with the OBDII reader connected and engine running. Suddenly engine switched off by itself. Pressed Start button and transmission returned to park. Now car is totally off but parking lights are on. Key fob works normally for all other functions. NAV screen illuminates but car won't start. Parking lights still on even with switch in OFF position.

Car is routinely connected to CTEK unit (as it is now, parked with lights on).

Suggestions? Disconnect battery and start over?

Thanks!

 

Your disconnect is a good place to start. Once one cable is off, momentarily touch it to the other cable to discharge all the capacitors. Make SURE you don't short out to the battery though, big problems if you do that. Best way would be disconnect the positive cable and short it to ground.

 

Thanks. Disconnected battery/reconnected and all was well once again. Then had CEL on again, inserted OBD reader and had Code U0100 - Lost Communication with ECM/PCM "A".

Restarted again and CEL went away, but OBD reader app won't connect to reader any longer. Faulty unit perhaps?

 

It's possible and not uncommon for the car to go into limp mode or die altogether as yours did. Sometimes the scanners just pulse and/or surge and lose communication in the middle of an action. Battery voltage can be a cause.

I own a model that will send the car into limp mode if I pull the unit out of the port before shutting off the vehicle.

 

Try pushing on the brake really hard when you attempt to start it

 

Alternatively, press the START button first, then tap the brake pedal. You shouldn't have to press the brake pedal very hard.

This works best after the car has been sitting overnight, without touching the brake pedal. It won't work if the brake pedal is already high and feels very hard.