EV mode with CEL

From your last sentence, I get the impression you want to install the EV button so that you can manipulate the engine to turn off, when it otherwise wants to run, in order to get better fuel economy.

If I am correct, you can save yourself the trouble as it won't achieve that goal.

The EV button is not designed to do that. When the engine is cold, it is to keep the engine off for short movements - say, in and out of the garage or to move around on your driveway. Another legitimate use is driving in a semi-enclosed parking structure with poor ventilation. In this situation, most of the time you will not need it as long as the engine is at operating temperature.

In stop-and-go traffic, it won't make much, if any, difference when the engine is at operating temperature.

On 30 MPH roads, you will not be able to use the EV button unless you are willing to travel 26 MPH (true speed*) or less. This is the speed threshold where EV mode will be forced off.

The other thing to bear in mind in these two scenarios is you're robbing Peter to pay Paul. All energy stored in the battery is derived from burning gas. Together with the energy conversion losses you will always be behind the 8-ball and your fuel economy will be worse as you will need to replace the energy taken from the battery by burning gas.

Further consideration should be given to the shortening of the battery's lifespan by forcing more battery cycles. I believe this was the prime consideration for the EV button being deleted in the NA offering. It was deemed necessary to enable providing the required 15-year warranty.

Those are some of my thoughts having had an EV button as standard fitment from the get-go.



* The true speed is shown on the vehicle signal check screen and is displayed in km/h. The displayed speed for that threshold is 42 km/h.

 

I appreciate the forthright candor of your reply and had you not included the last paragraph it certainly would have come off as aggressive and harsh but I totally understand your frustration.

In my defense, I generally do not post when I don't know the answer to the question(s) asked, and in this case, I have never had a MIL (CEL) and thought to try and see what the EV button behavior was, so I didn't answer the question.

Given that the information that you have since posted above was not available to me, you left me to assume your skills, training, abilities, expectations, and research history. Maybe that is a mitigation, maybe it is not.

Anyway given the research you've done, you probably know more than anybody on this subject. The pool of people that might be able to help is going to be small given how many people in the US might have added the EV switch and adding those people to the rest of the world then number then having a CEL and thinking to try whether they can use the EV button.

Cheers, and all the best.