Hi everyone!
I need some advice and guidance on what to do with this check engine light coming on. (Sorry, I can't seem to upload the image here - upload gets stuck at 90% completion.)

I had my car windows tinted. They used ceramic coating tint film (not metallic) so it would not interfere with any electronics.
When I turned on the engine, the Check Engine Light and icon came on - I asked the technician why it came on and he said they had to disconnect the battery and reset it.
Since the job took like 4-5 hours to complete, the car settings have reset.

He advised me to drive it around for a few days and it should resolve itself. I have my doubts though.
I can of course just take it to my dealer and have them take care of the light.
But I was wondering if there is an easy way or procedure for me to do it myself since it's just a battery disconnect and reconnect situation.

Any suggestions or recommendations would be most appreciated.
Thank you, Bernard

 

Did you check the message in the infotainment screen what was the fault? It's possible that the 12V battery was low while they try to start the car causing electronics to try to start up and it failed causing the engine light.

 

Yes, simply disconnecting the 12 volt battery was a very bad idea for the shop. While the battery may not have drained very much possibly, it most likely lost settings in the car, including maybe your personal settings like seat position radio stations, your phone connection to car etc. Most likely driving the car for a few 20 minute plus trips will clear the fault as the car recharges the 12 volt battery and all the internal scans should clear any other temporary faults as systems recover. I had this happen when I drained the battery myself and the check engine light cleared after several trips. I did call the dealer too and they confirmed if that's all it was the car will clear itself of any faults as they would no longer exist.

 

Never heard check light comes after tinting.best option is to hook obd scanner or wait if it clears itself.maybe they messed smth up

 

The fact that the car was in for tinting is totally irrelevant, the fact that they disconnected the 12 volt battery for 4 hours is the problem. This battery runs everything in the background needed to keep the car 'active' for over the air updates, theft deterrent protection, looking for a smart key to start it up etc. Afterwards all these systems must reinitiate themselves and that's what throws up the check engine code.

 

As the 12 volt battery would totally deplete with all the car doors open for four hours. Ideally they could have put a charger on the battery for the duration.

 

Get yourself a OBDII scanner and just erase all the error codes. Since they disconnected the battery, you will get a bunch of codes as a result now.

 

Hi everyone, just a quick update on my car "Check Engine" light status.
The short of it is, the technician was correct to just drive my car around. That resolved the issue. I drove it around town, stopped and started a few times, the check engine light is now off and error message is now gone. I am all set.

Here's some more detailed info:
** I checked the Infotainment system, and went through all the settings and configuration. I did not lose anything despite the battery being off for 4-5 hours, except for one. While my iPhone showed it was still connected, the Carplay was off, so I just had to turn that back on again. Whether that played a part in the check engine light being one, I don't know.
** The tinting itself did not cause the check engine light on, it was the battery being disconnected. Tint technician did state that is for extra precaution that they disconnected it. Since they're official installers for Lexus here where I live, they did state that they expected the check engine light to turn on and just advised me to drive it around and it will resolve itself. They were right.
** I rechecked all my previous settings, even my lights, sounds, my seat preferences, etc. all are intact and no information was lost despute 4 hours disconnection (save for the Carplay being disabled which I just had to re-enabled easily).
** I did ask my ChatGPT AI and it actually was pretty comprehensive in its response consistent with the technician's comments. ChatGPT advise to do two things: (1) drive it around for a while, and (2) check that my gas cap is tightened. ChatGPT did suggest that I use a OBDII too or go to dealer if the suggestions did not work. ChatGPT noted that a static check engine light being on typically is not serious and should resolve itself through some driving, it's only when it's flashing that would indicate a more serious issue.

Thanks again everyone for all your insightful feedback, thoughts, and suggestions. Driving it around for a while did resolve the issue.

Much appreciated, and stay amazing everyone!

 

Almost funny - how much time and tools are needed to disconnect the battery vs just clipping on a cheap charger from wally world. And a lexus cert’d installer at that - not very professional. Glad it came back up easy enough.

 

Look at what @TheCDN said in post #3, when they tinted your car it sounds like they probably disconnected your 12 volt battery. I am not sure why you would need to disconnected the 12 volt battery to tint a car ??

YMMV,
MidCow3

 

Yeah, I didn't think it is common practice to disconnect the battery during a window tinting installation, even if in my case, the windshield was also involved.

So based on what I have gathered... Disconnecting the battery during car window tinting, especially on modern vehicles like my 2024 Lexus 350h hybrid SUV, is not a universal or strictly necessary practice for window tint installation.

Here’s why some shops might do it, even though it’s generally not required:

Common Reasons Shops May Disconnect the Battery

• Preventing Electrical Issues from Moisture: Tinting involves spraying water or soapy solutions to apply the film. In modern cars with electronic controls inside doors and dashboards, technicians may be concerned about moisture causing short circuits or triggering sensors. However, water intrusion causing significant electrical problems is rare if the work is performed carefully.
  
• Avoiding Battery Drain: Tinting often requires repeatedly turning the ignition to accessory mode to operate power windows. This can drain the battery if the doors are open for extended periods (interior lights stay on, electronics stay active). Some shops opt to disconnect the battery to avoid customers returning to a dead battery, especially if the battery is already weak.
  
• General Electrical Safety: Some technicians feel safer working near active electronics if the battery is disconnected, though this is more of a concern for invasive electrical work (not tinting).
  

The consensus among professionals is that the:

• Battery should not be disconnected just to tint the windows, unless you have a specific electrical issue that requires it.
  
• Simply minimizing time with the ignition/accessory on, and using a battery maintainer if necessary, is the standard approach.
  
• If a shop always disconnects the battery “just in case,” it's generally out of extra caution rather than necessity or manufacturer guidance.
  

So with all that said, I guess it's really not necessary beyond maybe for the reasons above, even if I am based in Hawaii.

 

Lexus has a significant battery drain problem especially on the hybrids. I have hear some tinting shops that take hours to put the tint on have drained the Lexus battery in the past when leaving it in ACC or sometimes even having windows doors left open. If the tint shop has ever been burnt with a 12 volt battery dying and having to be responsible for replacement/damage I can see why they might update their policy to disconnect the 12 volt battery. In my case, Lexus service killed my battery in the car wash.. go figure.

YMMV,
MidCow3