2008 w/ engine light on

The B1S1 sensor is an air/fuel ratio sensor, not an oxygen sensor. I suggest that you purchase the correct Toyota part. P0031 and P2195 both relate to the failure of B1S1.

P0136 relates to the B1S2 sensor, and that is an oxygen sensor.

 

Jesus Christ! What are you?

 

Patrick Wong is in disguise, he probably built this car LOL

 

Nope. Not Jesus Christ.

Wong, Patrick Wong. I don't know who you are. I don't know what you want. If you are looking for Prius troubleshooting or anything to do with the Prius, I can tell you I will save you a ton of money. But what I do have are a very particular set of skills; skills I have acquired over a very long career. Skills that make me a nightmare for Prius problems. If you thank me now for the answers I gave you, that'll be the end of it. I will not look for you, I will not pursue you. But if you don't, I will look for you, I will find you, and I will kill you.






(If you havent seen the movie "Taken" then what I just said will make zero sense to you, lol)

 

It might be covered, check the maintenance and warranty booklet that came with the car, or call your local Toyota dealer's service dept to confirm.

You are correct that the inverter needs to be removed for access to the air/fuel ratio sensor, so this is not a minor project.

 

I have found that 02 sensor problems can be intermittent. O2 sensors are very reliable but they do go bad periodically. It is my personal belief that many O2 sensors are replaced unnecessarily. If I don't have any lights, I'm not replacing it for good measure unless its really easy to get to.

 

Lynn here,143K miles for I forget, I have a thing where the mpg has dropped a lot, 'bout 7 mpg or so was 43-43 now 36 or so AND the tail pipe has so much black soot it's like wood stove chimney, I mean when I wipe my finger around the inside the soot piles up on my finger, doesn't just coat my finger a little (I don't know how long that's been collecting) so went to auto parts store for something else and mentioned it and was told a drop of 5-7 mpg is indicative of an O2 sensor. Also the engine has been idling really rough and power has dropped some...so I took it to a mechanic, lovely bride insisted after I'd changed the plugs with no improvement (142K on original plugs) but honey I want to do the pcv also, anyway mechanic says air mass meter needed cleaning and it needed a new air filter, which I was going to put on anyway AND I'd already cleaned the air mass meter w/air mass meter cleaner, that spray stuff....but he had the computer on it before and says after HE did it the puter says it was up to 100% which it had been a 70 something% sooooo. I haven't driven it much but it doesn't seem to have improved much if at all on the little I've driven it.

1. rough idle with drop in mpg and sooty tailpipe, I'm thinking it's running way too rich, eh?
2. changed plugs and air filter and cleaned air mass meter (now at 100% , he says)
3. I've got a new set of fuel injectors in my hot little hand and this forum says "a child could do it" so I want to do that AND I bought a new "downstream" O2 sensor (don't aske me why, I read something bout it affecting running and fuel economy, tho now I read it's the "upstream" one which is more likely) this part of story reminds me of one time, at least, I was asked why I went to a certain place to check for trouble to fix a problem vs the more likely place and I replied "because it was easier to get to", and it may have been the place tho highly unlikely. ever notice the trouble is ALWAYS the last place you go? So I'm looking for help in replacing the O2 sensor, got the downstream one and if that don't do it I'll do the upstream one. Any suggestions?

 

What warning lights are on, and what DTC have been logged by your car?

The purpose of the downstream O2 sensor is simply to provide feedback to the engine ECU regarding catalytic converter efficiency. That sensor has nothing to do with engine management.

So, if you want to improve engine performance, you need to replace the upstream air/fuel ratio sensor - assuming that a DTC was logged which relates to that part.

 

Mr. Wong, I don't have a DTC that I know of, I checked it once with a mid range OBD II was a "something" 3100, can't remember, anyway the mechanic I took it to said no codes, that being said the tailpipe being sooooo sooty makes me believe it has/had to be running way rich for some time. That being said I've got the injectors and am gonna put 'em in, will see. Thanks for the response. Lynn

 

Been there, seen that....It was awesome. So many times in my life I would've loved to say something like that but then I just forgave them their whatever toward/at me and went on my way. (course they didn't do to me what happened to this guy in the movie! else would've tried to do what he did!)

 

"I don't have a DTC that I know of, ...anyway the mechanic I took it to said no codes, that being said the tailpipe being sooooo sooty makes me believe it has/had to be running way rich for some time. That being said I've got the injectors and am gonna put 'em in, will see."
OK. When you replaced the iridium spark plugs, what did the old ones look like? Did the porcelain insulators show tan combustion products or were the insulators more on the sooty side? Did all the plugs look the same or did some plugs look worse than the others?

If the old spark plugs looked OK and the check engine light is not on, then it is not clear to me that replacing the injectors will help.

I think that you should clear the mpg indicator on the MFD, then take a 50 mile or longer freeway drive, at 60-70 mph, and see what mpg is logged.

 

So sorry for taking so long to reply, but eh my problem, anyway I ended up R&R'ing the fuel injectors which looked, well, not good....gunked up or something only one being good looking...funny the far right one (looking from front of engine to rear) leaked like crazy the first two times I seated it/installed it so then I swapped the far left one with the far right one for the heck of it and wa la no more leak and guess what? MPG went up to 49mpg!!! yes clogged, shitty fuel injectors were costing me approx. 12-13 mpg go figure! never figured out why the one fuel injector was leaking in that hole, I installed 'em the same each time, making sure they were well seated, but hey all good now....well not exactly as now I am up to 150K miles + and am getting a intermittent "check engine" light....owners manual said to replace fuel cap and as it did seem to not tighten correctly I did but tho check engine light went out it then came back and now comes and goes, gas mileage is still nice 48.6 tho is much colder and all, not running the ac tho....I haven't gotten 48+ mpg for years and years like since the first time I replaced the tires with the wrong kind (mpg went down to 45-46)and then had a tuneup done (mpg went down more to 44-45) so I am FAT, dumb and happy and really not caring about the check engine light as we don't plan to sell the car for years, but did have the code checked and it said p4020 I think, it was catalytic/emissions related as I recall, it's been a couple weeks since we did it. Soooooo, am thinking will just leave it be for now as it's mostly off but I do have a "downstream" o2 sensor I'd purchased back when the poor mileage was happening, please don't ask why, I may try that as I'm rationalizing that if the o2 sensor after the converter wasn't working right or there was a loose/bad connection that could "throw the code" because it might be saying the converter wasn't working right? Maybe? probably not,eh?

 

Oh I forgot I'd also read somewhere, not sure it here, that a prius mechanic bought a used prius cheap because I think it wasn't running right and all he did was replace the fuel injectors, it may have been there, that story, that I read prius' are known for having to replace fuel injectors, some even under 100K miles..just sayin'

 

I'm glad that you found that the fuel injectors were the cause of your car's poor mpg.

Being exposed to an excessively rich fuel mixture for so long may have permanently damaged the catalytic converter.

Replacing the upstream air/fuel ratio sensor might help the engine ECU to decide the cc is OK. Replacing the downstream oxygen sensor probably won't help that.

 

Hi again, sorry for not following thru with the chat but that's how I am... Squirrel!...that's a joke from a cartoon/movie..anyway, the check engine light is still on pretty much all the time...it does go out for a day or so or a trip or so but comes back, I think I do have an "upstream" sensor I got before I fixed the low mpg problem, for some reason I said last year I had a downstream one but now think I was incorrect as I remember ordering the upstream one, will have to double check part numbers and verify. I want to try to put that in but am not sure it will help with a P4020 code....this Prius has been burning oil since day one, I was surprised to read in the manual to expect 1 quart or so of oil usage between oil changes but mine has used more than that I am sure, especially when considering I change the oil every 3500-5000 miles tops. the book recommends 7500 miles but that doesn't make sense as I thought it was common knowledge that city driving,i.e. starting and stopping driving is harder on engine oil life vs continuous, steady engine rpms like highway driving, well the Prius does just that what with the engine starting and stopping all the time I've found if I let go to 5k miles between oil changes the oil is very black and obviously thicker...anyway that's this layman's opinion...oh, just remembered a friend of ours bought a Prius V and it doesn't use any oil between changes and he let's it go 5k miles plus (he bought their "maintenance plan" as he didn't want to deal w/it and it seemed to be worth it)
TO QUOTE THE MANUAL PAGE 323: Oil consumption: Max. 1.0L per 1000km (1.1 qt/600)miles!!!!! Exclamation marks are mine!
When I think of all the oil this engine has burned thru and put out to the catalytic converter I have to believe I'm driving an engine working more like the old "oil-injected" outboards that Mercury and others used to make in the 60's and 70's. So I've just convinced myself that yes, it's probably the catalytic converter that's just exhausted, pardon the pun.

 

up!