ECU sometimes doesn't turn on nor show the yellow off symbol on the dash. How do I make this permanent as I hate the ECU feature.
Thanks

 

ECU stands for Electronic Control Unit, and their are a host of them on your car.

Please be a little more specific and perhaps we can help.

Thanks

 

I think the OP meant ECO, not ECU. ECO is the stop/start system that began with 2013 models. It activates automatically when you start the engine, but you can disable it by pushing a button on the dash, which then illuminates a yellow "ECO Off" icon in the instrument panel. When you shut off the engine the system resets itself instead of permanently disabling the system. It's a PIA to have to press the "ECO Off" button every time you start the engine. The OP asked if there is a way to permanently disable that system.

I think the only way to do so is to disconnect the small auxiliary battery in the trunk, which is used for the stop/start system. But I don't know if doing so would cause other problems.

It appears that the system functionality depends on the weather. I noticed that the ECO system on my 2013 XJ 5.0 SC doesn't activate (shut off the engine) on very cold days when the snowflake symbol is illuminated. I always keep my XJ plugged into my CTEK battery maintainer, so a low battery isn't the reason for the ECO system working intermittently. Another thing I noticed is that the system is sensitive to the amount of force on the brake pedal. The greater the force, the sooner the engine shuts off.

I'm OK with the ECO system, particularly when I know I'll be stopped for a while. Restart comes with a little vibration, but it's not that obtrusive. And it's hardly noticeable when the music is cranked up.

Stuart