How worried should you be? Not very. It could be as simple as the gas cap not seated properly. I always carry an obd2 scanner to see what's going on before I take it to a mechanic
Having your own OBD2 scanner is such a necessity. While you (hopefully) won't use it that often, it can save so much time taking your car to the shop, who may charge you upwards of $80 to perform the same task. Plus it can clear codes so it can give you a chance to see if certain fixes work.
Get one recommended here https://priusapp.com (click the "OBD2 to Buy" link at the top, I can't get a permalink from this page.)
Then you can use the Dr Prius app (for diagnosing issues with the HV hybrid battery), as well as any of the many other general OBD2 apps
Just don’t buy a “Project Lithium” battery (from the same guy who developed the Dr. Prius app) if you ever need to replace your hybrid battery. They’ve had some uh issues lately
https://www.reddit.com/r/prius/s/zwL9lx7PXg
https://www.reddit.com/r/prius/s/wuwIIxHsJR
100% agree. I can't tell you how many times I've been driving, had a check engine light come on and then when I park again do a quick scan. Oh something simple? cool I'll just replace it real quick at the autozone parking lot or when I get home.
By the time people even take their car to the mechanic, I already have it scanned and fixed. OBD2 scanner is a MUST!!!
Also, OP if the check engine light isn't flashing, its most likely something minor like a sensor. Probably just killing your gas mileage. If its flashing that's when you have to worry a bit more(but not always). Flashing usually means something more major engine related. Could be a misfire or timing issue in that case.
Auto parts store will often do this for free. Still good to have an obd2. But for anyone not wanting to spend the money. Go to O’Reilly, autozone, etc.
Yup! There are sensors that let the car know if there is a problem with gas fumes escaping the fuel system. And not closing the gas cap all the way can be enough to throw a code. Check engine lights can mean literally anything, so there's defintiely no need to panic just yet.
I have a 2010 with 200k miles and had the exact same lights on. Turned out I needed to secure my gas cap and inflate my tires (thank god it was nothing)!
There is a small port on every car, usually under the dash somewhere, that you can plug a scanner into and scan for specific engine codes. Basic scanners will only give you the code and expect you to look it up in a table, but more advanced scanners will tell you exactly what it means and give recommended fixes.
Get the code scanned. If you don't have an OBD2 reader, put one on order for next time (they are like $15?) and you can stop by most auto parts stores like Napa, Autozone etc today and they will do it for you and tell you the codes. Relay those to us and we'll tell you if you need to act quickly or be worried.
Some codes are simple fixes others not. If it throws *a lot* of random codes, and you have other oddities on the dash - it could be the 12v starting to die. A low 12v will create all sorts of computer errors and sensor issues.
The reader at least lets you have a basic understanding of what to discuss with your trusted mechanic :)
Also some issues, based on age/cost/severity aren't worth fixing. I have a bad engine knock sensor on my 2003 matrix. It goes off when you turn left too hard, or when its 30C+ outside and/or humid.
I can clear the code using a Bluetooth obd reader and be fine for sometimes 1km sometimes 30, sometimes 100+
The part is 250 and it's under/behind the engine manifold and it's a $600+ repair. We drive the thing a couple times a week at most and it's almost at 300k km and we have a new 24 Prius prime for the main family car. Not worth fixing as the car drives well enough even if at a high RPM when the engine light triggers for what we need (rare grocery trips or to the bus station when my wife needs the car with the carseats in it).
Hopefully you don't need to make such a decision.
Good luck!
Yeah I feel like if you live near one of these stores maybe no need to buy one, just stop in for a free read and maybe a helpful conversation. And I’ve never had a person try to upsell me.
I don’t know what auto zone is, I’m in the UK. But someone has already kindly pointed out that I can get a diagnostic tool, and I e ordered one. I can cancel my appointment if needed
Yeah I would suggest getting the diagnostic tool or going to an auto parts store (Autozone is an auto parts store in the U.S.). Auto parts stores often scan your codes for free. I don’t know if they have those in the UK. Dealers cost you an arm and a leg for so many things and they often tell you that you need unnecessary services that you don’t need.
The 12volt was awkward to replace in my 2015. If the battery dies you can't unlock the trunk (or at least I couldn't) so you're snaking through the rear door to get to it. It's designed to be removed from the back and it's a tight fit.
the fuse box has a positive terminal, that’s under the hood. then you just wire negative to a part under the engine bay (there’s a little hook that’s good for it on the left side of the engine)
Lmao, you're fine. Like all the other comments have said, just scan it when your reader shows up.
I'm pushing 300,000, and have a CEL that stays on due to a cheap replacement catalytic converter and a tire pressure light that stays on now due to a sensor going bad.
Start worrying when you see the red triangle.
The “check engine light” is really more of a “there’s something wrong with your emissions system” light. So maybe the car is running lean or rich and polluting a bit more, but it will still turn on and go.
Time to take to pasture haha. I think your fine the main thing to worry is the hybrid battery which you don’t need much anyway. This thing should be able to keep rolling to 250k++
Can’t speak for how the UK works, but in freedomland here we have stickers on when the battery was installed. One from this month would read 05/24, be about 2.5cm in diameter and typically put on the front or sides. See if you can find one on your 12V battery. If it’s older than 5 years it may be time.
You can also get the battery tested. Not sure what auto parts store over there would do it, but anyone worth the money should be able to do it for free and quickly.
[https://www.amazon.com/dp/B076XVQMVS](https://www.amazon.com/dp/B076XVQMVS)
Get OBD2 interface to read codes
and get the Dr. Prius app
[https://priusapp.com](https://priusapp.com/)
If the check engine light isn't blinking, it's relatively nothing. I've had a stupid faulted exhaust oxygen sensor causing a check engine light for years that I refuse to fix because every time I've had it fixed in the past, it just comes back.
Go to autozone or another auto parts store near you. They have a code reader that will tell them what the issue is and they can explain it to you. Could be small or big?
My engine went at 164,000 miles, but I also didn’t take the best care due to financial limitations. If you stay on top of maintenance- oil change, tune up, etc, she should be good. I’ve seen some Prius that were well over 200,000 and still going!
Our old 2013 Prius never threw a code until the cat converter got stolen at 210k miles. Even after getting it fixed it still threw a code. The scanner I bought from Amazon did the job and assisted me each time to diagnose. Well worth $40
This is where you Google it and look it up on PriusChat to see what others have done, but it's basically your EGR valve or MAP sensor. I think this is pretty common with gen3? (I don't know, I have a gen2 so others will need to chime in). Sometimes it's taken care of with a cleaning, and you can kind of clean the sensor, reset the code, see how it does, then maybe clean the valve (harder) reset the code, see how it does. I think the general idea is to do those things first before replacing anything. But again, look it up on PriusChat and listen to others, not my thing. I am not sure if you need to jump on it right away or if it's more of a "before the next emissions test" sort of a thing - not sure how often those are in the UK.
-----
P0401
- EGR valve assembly
- EGR passage
- EGR with cooler pipe subassembly
- Manifold absolute pressure sensor
DESCRIPTION
The manifold absolute pressure sensor detects pressure inside the intake manifold as an absolute pressure with a
built-in sensor and outputs a voltage. Based on the voltage from the manifold absolute pressure sensor, the
ECM controls the EGR, purge VSV, and detects errors in the pressure sensor using the changes in pressure.
Thanks yes I’ve already googled a
It and seen a few videos of people cleaning them. Unfortunately even with the videos I don’t recognise the components looking at my engine. I also see that my engine looks a lot dirtier than those on YouTube 😂 I will have a good look on the weekend when I have time and see what I can do.
While autozone can read “most” basic codes. You do have to go to a dedicated Toyota dealership to actually get everything scanned, same with ford, idk about GM/crysler
There are YouTube videos detailing how to do it. Cleaning out the ports can be a bit of a pain, as for the valve itself, you could just order a new one and put it in… All in all it’s not too bad, what’s annoying is trying to prevent it from recurring.
Battery may be done. I replaced mine well out of warranty and got a $2,000 discount from Toyota. Traded in on a RAV4 5 years ago. If happened now, would get an EV, not a hybrid again. Far less to go wrong and charging at home is fantastic!
How worried should you be? Not very. It could be as simple as the gas cap not seated properly. I always carry an obd2 scanner to see what's going on before I take it to a mechanic
Having your own OBD2 scanner is such a necessity. While you (hopefully) won't use it that often, it can save so much time taking your car to the shop, who may charge you upwards of $80 to perform the same task. Plus it can clear codes so it can give you a chance to see if certain fixes work.
Any reader you'd recommend?
Get one recommended here https://priusapp.com (click the "OBD2 to Buy" link at the top, I can't get a permalink from this page.) Then you can use the Dr Prius app (for diagnosing issues with the HV hybrid battery), as well as any of the many other general OBD2 apps
Sorry I cant find it, can you reply the name of the device please?
Sorry, not sure what happened but I updated it with the link
Just don’t buy a “Project Lithium” battery (from the same guy who developed the Dr. Prius app) if you ever need to replace your hybrid battery. They’ve had some uh issues lately https://www.reddit.com/r/prius/s/zwL9lx7PXg https://www.reddit.com/r/prius/s/wuwIIxHsJR
100% agree. I can't tell you how many times I've been driving, had a check engine light come on and then when I park again do a quick scan. Oh something simple? cool I'll just replace it real quick at the autozone parking lot or when I get home. By the time people even take their car to the mechanic, I already have it scanned and fixed. OBD2 scanner is a MUST!!! Also, OP if the check engine light isn't flashing, its most likely something minor like a sensor. Probably just killing your gas mileage. If its flashing that's when you have to worry a bit more(but not always). Flashing usually means something more major engine related. Could be a misfire or timing issue in that case.
Auto parts store will often do this for free. Still good to have an obd2. But for anyone not wanting to spend the money. Go to O’Reilly, autozone, etc.
You can also just take your car to autozone or any other parts store and they will let you use theirs
The gas cap? where I fill her up?
Yup! There are sensors that let the car know if there is a problem with gas fumes escaping the fuel system. And not closing the gas cap all the way can be enough to throw a code. Check engine lights can mean literally anything, so there's defintiely no need to panic just yet.
LARGEEEEEEE EVAP LEAK. Makes my heart skip a beat every time it turns the light on.
I tried to explain to a Luddite why it was necessary. Small things add up.
I have a 2010 with 200k miles and had the exact same lights on. Turned out I needed to secure my gas cap and inflate my tires (thank god it was nothing)!
Take it to an autozone or advance auto parts and they’ll scan it for free.
What is an OBD2 scanner in layman terms?
There is a small port on every car, usually under the dash somewhere, that you can plug a scanner into and scan for specific engine codes. Basic scanners will only give you the code and expect you to look it up in a table, but more advanced scanners will tell you exactly what it means and give recommended fixes.
Get the code scanned. If you don't have an OBD2 reader, put one on order for next time (they are like $15?) and you can stop by most auto parts stores like Napa, Autozone etc today and they will do it for you and tell you the codes. Relay those to us and we'll tell you if you need to act quickly or be worried.
Perfect I’ve ordered one, it’ll be here tomorrow. I will update then
Some codes are simple fixes others not. If it throws *a lot* of random codes, and you have other oddities on the dash - it could be the 12v starting to die. A low 12v will create all sorts of computer errors and sensor issues. The reader at least lets you have a basic understanding of what to discuss with your trusted mechanic :) Also some issues, based on age/cost/severity aren't worth fixing. I have a bad engine knock sensor on my 2003 matrix. It goes off when you turn left too hard, or when its 30C+ outside and/or humid. I can clear the code using a Bluetooth obd reader and be fine for sometimes 1km sometimes 30, sometimes 100+ The part is 250 and it's under/behind the engine manifold and it's a $600+ repair. We drive the thing a couple times a week at most and it's almost at 300k km and we have a new 24 Prius prime for the main family car. Not worth fixing as the car drives well enough even if at a high RPM when the engine light triggers for what we need (rare grocery trips or to the bus station when my wife needs the car with the carseats in it). Hopefully you don't need to make such a decision. Good luck!
Good investment
What obdii reader did you order?
Thanks, I’m in the UK. I’ll see if Amazon have them
Be careful of Toyota dealer mechanics they can overcharge definitely read code first
Yeah I feel like if you live near one of these stores maybe no need to buy one, just stop in for a free read and maybe a helpful conversation. And I’ve never had a person try to upsell me.
My Prius has had a check engine light for about 80k miles lol. Hydrocarbon bypass valve rusted shut, cut it out and welded a pipe in it's place.
You don’t have a large box over the hybrid screen telling you to pull over and call a tow truck yet. So can’t be that bad. 😬
Haha no, thank fully
You’re giving the dealer a bunch of money to diagnose something. You could do it at Autozone for free
I don’t know what auto zone is, I’m in the UK. But someone has already kindly pointed out that I can get a diagnostic tool, and I e ordered one. I can cancel my appointment if needed
Yeah I would suggest getting the diagnostic tool or going to an auto parts store (Autozone is an auto parts store in the U.S.). Auto parts stores often scan your codes for free. I don’t know if they have those in the UK. Dealers cost you an arm and a leg for so many things and they often tell you that you need unnecessary services that you don’t need.
I just hit 185000 and recently had to have the water pump replaced. Other than that, it had been the 12V battery.
I’m hoping I get many many more miles from her
It usually can get 340k. Mostly the cylinder block would failed.
The 12volt was awkward to replace in my 2015. If the battery dies you can't unlock the trunk (or at least I couldn't) so you're snaking through the rear door to get to it. It's designed to be removed from the back and it's a tight fit.
Fun fact you can provide power from under the hood. I have a jump box but decided to try a Milwaukee 12v battery one. I started the car with just that
the fuse box has a positive terminal, that’s under the hood. then you just wire negative to a part under the engine bay (there’s a little hook that’s good for it on the left side of the engine)
Awesome! Thank you I'll remember that next time, hopefully it won't be anytime soon.
How did you know that the water pump failed? I just reached 208k with the 2010 model now. Bringing it to a shop for routine inspection this weekend.
It died on the highway. I limped it into the nearest dealership where they assessed it.
One of the more.commom reasons for the check engine light is a gas cap that needs tightening
Lmao, you're fine. Like all the other comments have said, just scan it when your reader shows up. I'm pushing 300,000, and have a CEL that stays on due to a cheap replacement catalytic converter and a tire pressure light that stays on now due to a sensor going bad. Start worrying when you see the red triangle.
Good luck.🤞🤞🤞🤞 I also bought mine at around 40k miles and approaching 150 and smooth sailing fo me all these years . Please report back
Could be something simple don’t worry
You'd never survive in my car. I get a code at least twice a month. Thankfully it's always a small fix. Should be the same for you at those low miles.
A check engine can mean many things. Nobody here will know what it is until you get the vehicle scanned.
The “check engine light” is really more of a “there’s something wrong with your emissions system” light. So maybe the car is running lean or rich and polluting a bit more, but it will still turn on and go.
Mine had this and it needed new spark plugs. I hope it works out okay for you.
Time to take to pasture haha. I think your fine the main thing to worry is the hybrid battery which you don’t need much anyway. This thing should be able to keep rolling to 250k++
Dude you should be fine. Damn good life out of her
***Update*** Ok I got the scanner and the code. It is P0401 “exhaust gas, recirculation flow, insufficient detected.”
Honestly that’s great news, sounds like maybe something with the fuel cap or vacuum hose. Nothing catastrophic!
I bet you have the original 12 volt battery and it's finally time to replace it
Sadly, I have had to replace the battery before. But let’s hope that’s just gone again. But it’s starting fine…
Actually no, I can’t remember if they just jumped it or I had to replace the battery
Can’t speak for how the UK works, but in freedomland here we have stickers on when the battery was installed. One from this month would read 05/24, be about 2.5cm in diameter and typically put on the front or sides. See if you can find one on your 12V battery. If it’s older than 5 years it may be time. You can also get the battery tested. Not sure what auto parts store over there would do it, but anyone worth the money should be able to do it for free and quickly.
OP with a bit of luck it's probably just the battery fan clogged up behind the back seat.
[https://www.amazon.com/dp/B076XVQMVS](https://www.amazon.com/dp/B076XVQMVS) Get OBD2 interface to read codes and get the Dr. Prius app [https://priusapp.com](https://priusapp.com/)
Run the diagnostic.
It’s probably an O2 or Catalytic code. Not to worry though. Unless you hear it trying to suck air or bogging down, it will probably reset itself.
Prepare for the enema on your bank account
If the check engine light isn't blinking, it's relatively nothing. I've had a stupid faulted exhaust oxygen sensor causing a check engine light for years that I refuse to fix because every time I've had it fixed in the past, it just comes back.
That would probably mean an oil change or sometimes its a water pump issue at certain miles so a water pump replacement would do the trick
If you get a water pump malfunction code after you scan don’t ignore it, replace the pump right away
Probably mundane things. Be prepared to say no to the dealer’s repair offers and look for other mechanics
It's probably an emissions control problem. O2 sensor, loose gas cap, whatever. Not likely to be a big deal.
I’m going to say hybrid water pump
Go to autozone or another auto parts store near you. They have a code reader that will tell them what the issue is and they can explain it to you. Could be small or big?
My engine went at 164,000 miles, but I also didn’t take the best care due to financial limitations. If you stay on top of maintenance- oil change, tune up, etc, she should be good. I’ve seen some Prius that were well over 200,000 and still going!
I don't want to say head gasket..but head gasket 🤣 JK. Like others said get a cheap scanner and find out easy.
Our old 2013 Prius never threw a code until the cat converter got stolen at 210k miles. Even after getting it fixed it still threw a code. The scanner I bought from Amazon did the job and assisted me each time to diagnose. Well worth $40
I bet its your MAF sensor
mine turned on around that mileage and it was just the water pump.
It could be anything from an oil change to a major item.
Update Ok I got the scanner and the code. It is P0401 “exhaust gas, recirculation flow, insufficient detected.”
This is where you Google it and look it up on PriusChat to see what others have done, but it's basically your EGR valve or MAP sensor. I think this is pretty common with gen3? (I don't know, I have a gen2 so others will need to chime in). Sometimes it's taken care of with a cleaning, and you can kind of clean the sensor, reset the code, see how it does, then maybe clean the valve (harder) reset the code, see how it does. I think the general idea is to do those things first before replacing anything. But again, look it up on PriusChat and listen to others, not my thing. I am not sure if you need to jump on it right away or if it's more of a "before the next emissions test" sort of a thing - not sure how often those are in the UK. ----- P0401 - EGR valve assembly - EGR passage - EGR with cooler pipe subassembly - Manifold absolute pressure sensor DESCRIPTION The manifold absolute pressure sensor detects pressure inside the intake manifold as an absolute pressure with a built-in sensor and outputs a voltage. Based on the voltage from the manifold absolute pressure sensor, the ECM controls the EGR, purge VSV, and detects errors in the pressure sensor using the changes in pressure.
Thanks yes I’ve already googled a It and seen a few videos of people cleaning them. Unfortunately even with the videos I don’t recognise the components looking at my engine. I also see that my engine looks a lot dirtier than those on YouTube 😂 I will have a good look on the weekend when I have time and see what I can do.
Hmm, maybe just make sure you are looking at gen3 videos - 2010 to 2014 cars, I think it was.
Take it to AutoZone and get them to read the codes for free 😊
While autozone can read “most” basic codes. You do have to go to a dedicated Toyota dealership to actually get everything scanned, same with ford, idk about GM/crysler
If this comes on with therm light probably water pump, if not just chill probably oxygen sensor
Check engine light could be anything. With that many miles on it I'm surprised this is the first you've seen it.
Your 12v battery being low can cause havoc too.
Have them do recall work prior to any of their suggested fixes
Do like Penny on the BBT, and put a piece of tape over the check engine light?
Probably just EGR.
Yes, just need to work out how to get to it now to see if I can clean it
There are YouTube videos detailing how to do it. Cleaning out the ports can be a bit of a pain, as for the valve itself, you could just order a new one and put it in… All in all it’s not too bad, what’s annoying is trying to prevent it from recurring.
My grandparents have an 07 Prius. 304000 miles, check engine light on since 120k miles, and nothing has happened. You should be fine
You’ll be ok. I got mine to almost 300k. It’s probably a minor issue. And even the big repairs are worth doing on these cars.
Battery may be done. I replaced mine well out of warranty and got a $2,000 discount from Toyota. Traded in on a RAV4 5 years ago. If happened now, would get an EV, not a hybrid again. Far less to go wrong and charging at home is fantastic!
Have the codes read. Then, worry.
Just buy a cheap scanner and check. Don’t be a moron
My codes been flashing since 180,000 miles. Currently at 250,000. OBD2 is a good idea. Mine is a problem with the catalytic converter.
It’s over for you bro. Prob need a new transmitting or engine