Two weeks ago a colleague told me I left the lights of my Prius on. I went back. Light switch was turned off, but dashboard showed that light was on and the lights outside were on. I restarted the car, put the light switch on and off again. 15 minutes later the car lights came on again. I took the car to the Dealership, diagnostic revealed nothing. I installed a new 12 volt battery, thinking that might be the problem. Two days later the same thing happened. This morning I came into the garage to find my Prius' lights on, switch is off, car was not running.

Meanwhile it has turned into randomly lights turning on and off and on again when car is parked and engine is not running, the door beeps when I open the car and sometimes I cannot even switch the lights off at all anymore. The dashboard light stays on, the outside lights stay on, regardless if I have the switch in on or off position. But, this is the deal: not always. Each time I take the car to the repair shop it acts like a nice mannered little child. Although I noticed when a couple of weeks ago the car needed 10 to 15 minutes to switch the lights on all by itself, now it manages it in 3 minutes tops. When it acts up, it acts up in spurts and toggles between lights off and lights on. But I can hardly get the lights to stay off when they switched on by itself, and other times it doesn't acts up for days in a row.

However, I noticed this seems to occur more on rainy days or 2 to 3 days after heavy rain. I am frustrated, because the mechanics come up with nothing.

Update from Jul 4, 2022: The car was not salvageable. I had it on and off at the dealership for 3 weeks. Then all the lights went crazy and got on and off randomly, not just the headlights. Finally it acted up at the dealership as well: they found out that the entire electrical component was corroded. Although it was a garage parked vehicle, water seeped in and destroyed the entire electrical component. Fixing it would have cost me over 4 grand with no guarantee that the problem would be solved, as they couldn’t figure out how water got in there in the first place. I was not even allowed to take the car back home to rethink my situation as to what to do, because it could have gone up in flames at any time. It was death trap. I decided to leave it behind and bought a 2016 Camry XSE from the lot. The Prius was a 2006 model by the way. In any event, it served me well for over 10 years. But it’s end could have also been my demise. Never a hybrid again after this debacle.

Overall, I have enjoyed the Prius I drive. I inherited it from my mother, who bought it new in 2008. She had problems with the headlight early on and they have continued for me. The headlight rarely works on the driver's side. I have already spent $500 trying to resolve this issue by replacing the entire headlight. The new light worked for 2 days and then the new headlight stopped working! Very unsafe situation on rural roads at night! I now read that this is a recurring problem with the Toyota Prius especially in the time period from 2006 to 2009. My car has high miles so I am not sure how to resolve this.

It all started in 2009 when I was pulled over for having a headlight out. I brought the car in to Toyota Riverhead where I purchased the vehicle. They told me there was nothing wrong with the headlamp. I then purchased a HID bulb at the advice of a local mechanic that i knew. He replaced the HID bulb and finally the headlamp was working correctly. When i called Toyota and told them i replaced the bulb and other parts of the assembly they told me to send in the paperwork and i would be reimbursed considering it was determined that there WAS DEFINITELY an issue with the HID HEADLIGHT nationwide I had received a letter from Toyota Motor Sales in Torrance Ca with a headline on the letter 2006-2009 MODEL YEAR PRIUS HID HEADLIGHT CUSTOMER SUPPORT PROGRAM. I NEVER WAS REIMBURSED. After many back and forth emails and letters - i gave up! It was like a full time job. Fast forward 2014 and the left driver side headlamp stops functioning. I bring it in and have it replaced at the cost of almost 400.00. June 2016 passenger headlamp starts flickering again!! I bring it in and am told that i need a new bulb AND A NEW BALLAST. Total cost with labor 550+. Luckily i have a file on the Prius and have reviewed all the paperwork and now realize that that headlamp will have cost me over 1000.00 once replaced AGAIN! I WILL NEVER BUY A PRIUS OR FOR THAT MATTER A TOYOTA EVER AGAIN. The reason i never brought the car in for service to Toyota Riverhead after the first 50,000 miles was they never owned up to the initial promise they made me when i purchased the vehicle -which was i would have a loaner car whenever i serviced the car. THAT NEVER WAS THE CASE. THEY NEVER HAD A VEHICLE AVAILABLE. I will use social media and my PRESS contacts to always discourage anyone from buying a Toyota. anyone have any suggestions on getting reimbursed???????

Context, I have only put 9-10K miles on car in last 15 months due to fair amount of travel....Front headlight was identified as being out by son 10 months ago. I checked and he was right, but turned off and on and it came back on. Seemed fine, got over it. Roughly 4 months later, same thing happens when friend states right front light is out. He watches me turn it on, looks fine, don't worry about it. Last week, six months later, I'm behind a vehicle at a stop light and notice right front light is out in reflection of rear panel on car in front of me. I turn off/on it comes back on, but when I get home I wait in front of garage door and watch reflection on door. After a total of 11 minutes it fades out....but then I can turn it back on and it lasts another 9 minutes.....so defective I think. Take it to Toyota and they want $632 to replace $300 bulb PLUS $300 in labor!!! They said I could go with a traditional bulb and save $200....!!! What a rip off! I don't want to cave and pay after reading people's stories here on line but don't want a ticket or worse either!!! May google youtube to see if there's a how to video!!

Getting ready for a 12,000 mile road trip, I took my Prius to the dealer for oil change, routine care, inspection, and so on. Everything checked out well. I put on a new set of tires. Two days later, one headlight went out. I made a new appointment, and got in the afternoon before my trip. They replaced the bulb. I asked them to replace both so I wouldn't risk the other one going out during my travels all over Canada and the U.S. (Starting from Alaska).

On the way home from work that evening, a driver coming from the other direction blinked her lights. Uh-oh. That was a mile from home. When I got there, sure enough, that left light was out again. Now I had a problem. I was to drive 300 miles to the Canadian border the next morning. The border guards almost always check headlights, as the law in Canada is to keep them on at all times. The dealer was an hour in the other direction, even if I could have gotten on their schedule that quickly. I was anxious about it, but I drove up to the border town, Tok. Maybe I could get this taken care of there, quickly.

I arrived in Tok at 4:30 Friday afternoon. At the gas station/garage, the fellow said all the mechanics had gone for the weekend, but there was a place down the road that might still be open. The place down the road did not inspire confidence in me. The fellow there took a look, fumbled around a bit as though he'd never seen a Prius before. He said the parts store was closed until Monday. His opinion was that the mechanics who put the bulb in handled it with their bare hands, and their skin oil caused a hot spot which caused the bulb to burn out. OK then.

Since I had made online hotel reservations, prepaid, all through Canada for the next week, I chose to drive on to the border and take my chances. I was lucky that day. The border guard asked me a couple of questions, glanced at my passport and waved me through. He didn't even ask for my expensive dog health certificate. Whew!

Well, 10,000 miles later, I'm in Seattle, and headed back across the Canadian border. I don't want to push my luck again. So far, I've driven exclusively during daylight hours, using my parking lights as highway compliance. I need to try to get the light working now. After reading the numerous complaints about this as a common problem, I'm very discouraged. I have planned to drive this car, which I love, for quite some time. Toyota!!! You should have issued a recall on this.

i started having issues with my headlights going out ... started on the right at first with a bad headlight which was replaced and seemed to go out randomly ... started to happen more and more over time .. my x had a crash which then most likely knocked something lose but im not totally positive.. this made my right headlight completely fail and the left to short out flicker or shut off randomly making it extremely dangerous and kinda deadly for me to be driving and with what i do for work and on the daily basis consists of a lot of driving... i finally replaced the bulb in headlights both right and left but was extremely disappointed in my online buy when one light turned green and another purple so i then put in whatever bulb i found that had been previously taken out.. after that the left side went out and flickers off alot i am constantly having to turn my lights on and off .. and they only work with my brights on... with the amount of healight problems for this year you would think it would get fixed and that toyota would put a recall on it

I READ 28 COMPLAINTS ABOUT THIS HEAD LIGHT PROBLEM AND THEY ARE ALL THE SAME INCLUDING MINE . ALL STATE THAT CHANGING THE BULB DOES NOT SOLVE THE PROBLEM.

IN DIGGING IN TO THIS PROBLEM I FIND THAT THERE IS A HID BALLEST??? AND THIS SEEMS MORE THE SOULTION I DO NOT KNOW IF THERE ARE ONE OR TWO " BALLESTS" AND AT 90 BUCKS AN HOUR I AM HESITANT TO LET THE DEALER SHIP ANALYZE THE PROBLEM. WITH THIS COMMON A PROBLEM TOYOTA SHOULD BE CHECKING IT OUT FOR THE SOLUTION. I REALY LIKE MY 2008 PRUIS AND CONSIDERING BUYING A NEW 2016. BUT I CANNOT SELL MY AND PASS THIS PROBLEM ON TO SOME ONE ELSE. IF I TRADE IT IN WOULD THE DEALER KNOWING RESELL IT AS A USED CAR WITH THE DEFECT NOT FIXED. OR WOULD THEY LOWBALL MY TRADE BECAUSE OF IT.THIS PROBLEM MUST BE RESOLVED

This has been an ongoing problem which started about one year after I purchased the vehicle. I can remember the exact date it started. I've lost time from work to have the bulbs replaced every couple of months. My mechanic now tells me I should replacement both headlight assemblies because the bulbs have been changed out too many times. These tie into the wiring harness; I'm told is a costly repair. Just the headlight assemblies alone will cost approx. $700.00.

This is serious safety problem! I would think Toyota would be concerned about liability! Wouldn't it be better to do a recall and fix the problem; it would be good public relations on their part.

Driving down highway just after dark, both headlights went out simultaneously. Checked the switch, it was on, and dashboard lights remained on. Fortunately was only a few blocks from home at that point, so when I got there I tried turning lights off and back on - they came on bright and immediately dimmed (but stayed on), which was normal. Checked online first to see if this had been reported by others and found this site - will contact Toyota next.

Update from Jan 23, 2016: Two calls, both lowered my opinion of Toyota.

The short version is that (after consulting with their master mechanic) they 'haven't heard of a problem like this' and would need to run some tests to find out what could cause it. None of the possible explanations Matt gave held any water: Bad bulb? (Not when they both drop simultaneously, and can re-light later.) Bad on/off switch? (not even touched) Bad socket? (Again, not when both go out at once) Bad ground? (Since it IS possible for only one headlight to work, they're grounded separately) Loose connection caused by going over a bump? (no bump)

Personally, I think it's a bad computer-controlled circuit, exacerbated by poor diagnostic capability - he said they can't just connect a diag. computer to it to check the onboard computer unless it's currently failing. That would make it easier, of course, but there should be some basic functions they can test. There isn't even a 'light failure' visible on the dash when light switch is on and headlights aren't - which is another indication that the computer's got dementia (along with the designer).

Mechanic suggested either driving it until it happens again and THEN bring it in while it's not working (yeah, that sounds safe and plausible...NOT) - and try turning switch on & off if it does go out (yeah, I figured that out - only (might) work when you KNOW they're out. That could also contribute to a switch problem) - or I can leave it with them and they'll park it with lights on & engine running until it fails...then begin the diagnosis process, which starts at $105. but goes up at each step after they rule out the easier stuff. Could be hours, could be days, may not even occur again - until of course the bulbs DO finally fail. In which case they'd fix that (at over $300. each), but it wouldn't solve the underlying issue.

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Took it into another Toyota dealer across town, who also hadn't heard of a headlight issue (other than requiring bulb or ballast replacement 'due to normal wear'. They couldn't replicate the problem, but what they could see appeared OK. Same advice: Keep driving, turn off & on if they go out again (and I can tell), or bring it back when not working.

We were starting out on a six hour drive on a vacation and noticed the passenger side headlamp was out. We modified our plans to only drive during the daytime whenever possible, and ordered a headlamp for $49.96 on Amazon.com, so we could replace it when we returned. On the drive back, we noticed that the headlamp had come back on! Then, I did some research and found out that this intermittent headlamp problem is fairly common in my 2008 Prius. Now, I'm not sure if the problem is the headlamp or some type of circuit problem. I will try replacing the headlamp myself the next time it goes out, and see if that fixes the problem. I have heard it is fairly expensive to have it done at the dealer.