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Ask Ron Z. Your Own Question
Ron Z.
Ron Z., - Toyota Tech -
Category: Toyota
Satisfied Customers: 19043
Experience:  18+yrs experience. State Inspector and Toyota Diagnostics
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I have a Toyota Highlander (2016) and my MIL is on, not

Customer Question

HI - I have a Toyota Highlander (2016) and my MIL is on
JA: Do you have the trouble code? Do you have a code reader or scan tool?
Customer: not really, it is just that malfunction indicator light
JA: Not a problem. You can work with the Toyota Mechanic to figure that out. What year is your Highlander?
Customer: 2016. Would I need to take the car somewhere to get the p-code or would i be able to figure it out by myself?
JA: Are you fixing your Highlander yourself? What have you tried so far?
Customer: done nothing so far. i am not fixing it myself but my highlander is out of the country (in west africa) where i had taken it when i moved. the toyota dealer here does not support highlanders (because it is a US model) - they do landcruisers and RAV4's and hence I have to guide them a little bit myself
JA: Anything else you want the mechanic to know before I connect you?
Customer: I assume you got my message above
Submitted: 2 months ago.
Category: Toyota
Expert:  Ron Z. replied 2 months ago.

Hi! Welcome to JustAnswer. Thanks for coming! I'm Ron and I'll be working with you on your question today.

Are you experiencing any engine performance symptoms like skipping or stalling?

Customer: replied 2 months ago.
No - no such issues. I just had the periodic service done earlier today at the dealership. The light had been on yesterday; had disappeared when I went to the dealership and just reappeared.
Expert:  Ron Z. replied 2 months ago.

Ok. Great. Please give me one moment to type out some info for you. Sit tight one minute... I'll be right back!

Expert:  Ron Z. replied 2 months ago.

Thanks for holding!

When the Check Engine light comes on, this is the on-board computer's way of telling you it sees a problem in one of the monitored systems. Unfortunately, there are literally 100's of parts and sensors monitored in various systems, and to take a "guess" as to which part/sensor in which system is faulty, is virtually impossible. However, if you are not experiencing any drivability issues such as skipping, stalling, shifting problems, etc, then more than likely, the problem is going to lie in the EVAP (emissions control/recovery) system. Very commonly, this could be a faulty, loose or missing fuel cap or even putting fuel in while the vehicle is running can set the light. Check the underside of the fuel cap for any cracks or signs of defects that may keep the cap from sealing correctly. If there are any doubts about the inspection of the cap, replace it. Keep in mind, you will need a cap that meets OE Specs. Those "universal" or "locking" fuel caps sold at after market parts stores do not meet OE specs, and will not seal the system correctly. Check the top of the fuel filler neck for any signs of damage or debris. Check under the vehicle, around the rear areas of the vehicle, looking for any vacuum lines that have dry-rot cracks, holes or loose/missing connections. If these all check out, then the best thing to do at this point is to have the Diagnostic Trouble Codes (aka "p-codes") read from the on-board computer. These p-codes are what is used as a "starting point" for the diagnosis and will tell which part/sensor, in which system, has the fault. Every single Mechanic's first course of action will be to obtain the p-codes. It's standard diagnostic procedure. Once you get these p-codes you can more accurately and efficiently diagnose the problem and then make the correct repair. You can have these p-codes read FREE (except in California) at any local "big chain" part store (ie. AutoZone, PepBoys, Advanced, etc).

In the meantime... As long as there are no obvious engine performance issues (like skipping or chugging) or shifting issues, then it is perfectly safe to drive the vehicle. You should however, have the codes retrieved at least to verify. If the problem does lie in the EVAP system, it is strictly for emissions control/recovery and will in no way effect engine performance in any way. If the problem lies outside the EVAP system, it may be a good idea to have it serviced as soon as possible, as prolonged driving with a problem with the engine or transmission can make matters worse.

Please be kind enough to leave a rating for our Q&A using the 'stars' at the top of the page or click 'Accept' when I have answered all your questions. A 5-star rating is very much appreciated! Rating or accepting my answer does not cost you extra.

Expert:  Ron Z. replied 2 months ago.

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Expert:  Ron Z. replied 2 months ago.

Were there any other questions I could help you with today?

Expert:  Ron Z. replied 2 months ago.

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Expert:  Ron Z. replied 2 months ago.

HI! I noticed this Q&A was still open, so I wanted to check in and see if there was anything else I could do for you on this? Any other questions you had?