Check engine light and O2 sensor on a Toyota Echo

[fuzzybabybunny]

I've got a 2000 Toyota Echo. Mileage is about 105,000 miles. About a month ago the check engine light came on, but because I was strapped for time, I didn't get it looked at for about another 500 miles afterwards. It ran fine during this. Gas mileage was the same, at least 40mpg.

I take it into a shop, they put the reader up to the OBDII to read the error code, and it says that there's something wrong with the O2 sensor. The mechanic resets the check engine light and tells me to drive it around for a bit to see if the light turns back on. Well, it turned back on after about 150 miles.

The cost of the O2 sensor replacement will probably be something like $200. My dad doesn't want to spend this money on the car and he wants me to disconnect the car battery to reset the light, or just ignore it. He had a bad experience with a check engine light problem before. The light came on, the mechanic "fixed" the problem with a replacement, but the light came back on again, and my dad was mad and out a couple of hundred bucks.

Recommendations?

locked after a necro bump from a spammer. -Admin DrPizza

 

[cprince]

If it's the O2 sensor, then you should replace it. If you smell something funny, like rotten eggs, while driving, then it's the O2 sensor.

 

[HiTek21]

You may not be able to pass emission testing with a check engine light on and it could damage your catalytic converter over time.

You could replace the O2 sensor yourself it's a pretty simple job but you need to know if its your front or rear o2 sensor. They sell universal type o2 sensors that have bare wires, you'd need to cut off the connector from your current sensor and splice it into the universal one, this is usually a lot cheaper than buying the OEM specific types.

 

[Fenixgoon]

you can run for a decent while without replacing the O2 sensors. mine spit out a faulty code, but after a day or two, the engine cleared the fault because the O2 sensor was no longer sending a fault code to the ECU, so it can be intermittent. but replacing it certainly won't hurt, especially if your CEL remains after a day or two.

 

[Bartman39]

Ok not sure where everyone gets their info but running with an O2 sensor either out of spec or not working at all is not good for any length of time... Reason... This is what tells the ECU how to trim the fuel system which directly affects the catalytic converter which is big bucks if left unattended... Also with OBDII you cannot just disconnect the battery and reset the ECU it has to be done via the scanner...

Also dont go with the "generic" O2 sensor (cutting wires and such) some of these have specific values and ranges of operation that work with the ECU... Toyota`s tend to be alot more sensitive to this and some just wont work with anything but the OEM sensor... So you end up spending the money and effort on a cheapy fix and thats what you get... Buy the OEM version and in most cases you can change it yourself... Some do require a special socket if they are in a hard to get area while others are in plain view... But along with this you normaly have an upstream and a down stream O2 sensor... (V8`s will have 4 while 4 cylinders have 2 NORMALY...!) Just depends on the system...


Not BS`ing you either I do this for a living (25+ year) so kinda have to be right...

 

[kt]

Originally posted by: Bartman39
Ok not sure where everyone gets their info but running with an O2 sensor either out of spec or not working at all is not good for any length of time... Reason... This is what tells the ECU how to trim the fuel system which directly affects the catalytic converter which is big bucks if left unattended... Also with OBDII you cannot just disconnect the battery and reset the ECU it has to be done via the scanner...

Maybe my cars are just special, but all the cars I have owned I was able to reset the ECU by disconnecting the battery. Down side to that is I lose any type of settings stored in memory along with it.

 

[Zenmervolt]

Originally posted by: Bartman39
Ok not sure where everyone gets their info but running with an O2 sensor either out of spec or not working at all is not good for any length of time... Reason... This is what tells the ECU how to trim the fuel system which directly affects the catalytic converter which is big bucks if left unattended...

It would take a _very_ long time for the lack of an O2 sensor to cause problems with the Catalytic converter. Any modern ECU will simply default to a "standard" fuel map when the O2 sensor readings are out of spec.

You'd need to drive for several years without an O2 sensor before you caused problems with the catalytic converter. In fact, the performance chip in my 951 completely disregards the signal from the O2 sensor and, shockingly enough, the car not only passes emissions with flying colors, but it also has managed to keep the catalytic converter healthy for the last 50,000 miles. (Original catalytic converter, the chips have been in the car at least 50,000 miles, car has 160,000+ miles on it right now.)

To the OP:

Fix the O2 sensor. It's pretty much guaranteed to be the problem and there's no reason not to fix it if you can afford it. Your father's worries really are unfounded.

ZV

 

[Fenixgoon]

<div class="FTQUOTE"><begin quote>Originally posted by: Bartman39
Ok not sure where everyone gets their info but running with an O2 sensor either out of spec or not working at all is not good for any length of time... Reason... This is what tells the ECU how to trim the fuel system which directly affects the catalytic converter which is big bucks if left unattended... Also with OBDII you cannot just disconnect the battery and reset the ECU it has to be done via the scanner...

Also dont go with the "generic" O2 sensor (cutting wires and such) some of these have specific values and ranges of operation that work with the ECU... Toyota`s tend to be alot more sensitive to this and some just wont work with anything but the OEM sensor... So you end up spending the money and effort on a cheapy fix and thats what you get... Buy the OEM version and in most cases you can change it yourself... Some do require a special socket if they are in a hard to get area while others are in plain view... But along with this you normaly have an upstream and a down stream O2 sensor... (V8`s will have 4 while 4 cylinders have 2 NORMALY...!) Just depends on the system...


Not BS`ing you either I do this for a living (25+ year) so kinda have to be right...</end quote></div>

at least with VW/audis (my brother is practically an audi mechanic with all the work he's done on his A4), a CEL means there *may* be a problem. if the fault code doesn't clear after a set amount of time, then there *is* a problem. but in my case, the fault code was cleared by the ECU because the O2 sensor stopped sending the fault code.

i drive a vw passat, fwiw

 

[Bartman39]

Fenixgoon... Without knowing the exact code it could either be the heater circut of one of the O2 sensors or the value side of it... (i drive a vw passat, fwiw... does China have a price on rice again...?)

Zenmervolt... If its the downstream O2 sensor then the ECU will not know what the cat is doing and can and will richen the mixture to the point of the cat melting... As for a default fuel map it will handle things to some degree, but if the driver has a rather heavy foot then the ECU will demand to richen the mixture hence a cat meltdown also... In addition stop and go traffic will speed up this process...

kt... Sorry but OBDII just dont work that way... The check engine light may go out but I assure you the code is sitll there...


Awhile back people never would have thought a coil wire to close to a metal bracket would cause a converter to meltdown... Might ask a GM tech about the 96-98 trucks with V6`s...

Just think of it this way with the crappy fuel we have and the crazy emissions standards its a wonder any of this stuff works any length of time... But also that O2 sensor is there for a reason and its not to just plug a hole in the exhaust... It tells the ECU whats going on with the fuel that just went through the engine and remember to much or to little fuel will cause expensive repairs...


Thought for the day... 1 drop of water turned into steam expands 7,000 times... Believe it or not...

 

[BaDave]

The upstream o2 sensor on toyotas are called air fuel ratio sensors an can be very expensive.The down stream o2 sensor just monitors the efficency of the converter.More than likely it is the upstream o2 sensor. As someone said before it could be the heater circuit in the o2 sensor which is a common failure.Either way ya should just have it taken care of.

 

[Zenmervolt]

Originally posted by: Bartman39
Zenmervolt... If its the downstream O2 sensor then the ECU will not know what the cat is doing and can and will richen the mixture to the point of the cat melting... As for a default fuel map it will handle things to some degree, but if the driver has a rather heavy foot then the ECU will demand to richen the mixture hence a cat meltdown also... In addition stop and go traffic will speed up this process...

The 944 has only one O2 sensor, and the lack of it hasn't caused death to my catalytic converter in over 50,000 miles of very hard driving.

I say again, it would take tens of thousands of miles of driving without a functioning O2 sensor to damage the catalytic converter. You overstate the risk by several orders of magnitude.

ZV

 

[Bartman39]

Zenmervolt...

The 944 has only one O2 sensor

Might consider this is not a Toyota and a total different system... Do you work on every model and make of auto/truck every day...?

You overstate the risk by several orders of magnitude.

I`ll go the Geico caveman route "Uh WHAT...?"

This is like comparing apples to oranges but again what do I know...? Just a lowly mechanic that has no degree but started working on engines in 1972...?

 

[kami333]

Originally posted by: Bartman39
kt... Sorry but OBDII just dont work that way... The check engine light may go out but I assure you the code is sitll there...

Actually depends on the car, some manufacturers do. I've been nursing a bad rear O2 sensor through inspections this way.

 

[kt]

Originally posted by: Bartman39

kt... Sorry but OBDII just dont work that way... The check engine light may go out but I assure you the code is sitll there...

Like I said, my cars are just special with "special" OBD2 or something. Sure, if there's a malfunction the fault code will return and the CEL will turn on. But if it was just a fluke or the malfunction got fixed then the code will not return and the CEL stays off. And I am aware of the OBD2 ready state. It will not be in a "ready state" until you drive the car enough for the OBD2 to make the appropriate evaluation to determine whether the malfunction it detected was properly repaired.

 

[Zenmervolt]

Originally posted by: Bartman39
Zenmervolt...

The 944 has only one O2 sensor

Might consider this is not a Toyota and a total different system... Do you work on every model and make of auto/truck every day...?

Do you lack the reading comprehension to understand that I pointed out that the 944 only has one to show that I understood that the systems were different?

Originally posted by: Bartman39

You overstate the risk by several orders of magnitude.

I`ll go the Geico caveman route "Uh WHAT...?"

If that's not simple enough for you to understand, I can't imagine how to make it any easier for you. You are overstating the risk to the catalytic converter. The OP would need to drive for tens of thousands of miles to do appreciable damage.

Originally posted by: Bartman39
This is like comparing apples to oranges but again what do I know...? Just a lowly mechanic that has no degree but started working on engines in 1972...?

Still doesn't make you right. There are many, many, many "mechanics" who have been working for decades that I wouldn't recommend even to someone I disliked, simply having been doing it for a long time doesn't mean you're right.

Driving the car for a month or two with the O2 sensor malfunctioning is not going to cause measurable damage to the catalytic converter. Is it less than optimal? Sure. But it's not the doomsday scenario you're making it out to be.

ZV

 

[Bartman39]

Zenmervolt... Your main issue is to argue so I wont waste any more time or text...


kami333 & kt... In a nutshell it may turn the light off but the code is still there... But just because the light is off doesnt mean the problem goes away...

 

[Pacfanweb]

Bartman, you seem to have some good, worthwhile knowledge, and it's good to see knowledgeable people helping out here.

However, I'm going to have to agree with ZV. You might not like his matter-of-fact approach, but he's right....it is not very common for a bad oxygen or cat monitor sensor to mess your cat up. Can it happen? Yes. Is it likely? No. If one of the sensors goes on the blink, the ECU will substitute a known-good reading until you get it fixed. That will somewhat eliminate the precise fuel-metering ability of an ECU, but it'll still get you around for a long time. You aren't in grave danger of smoking your converter. Usually what gets the converters is something else that messes up the fuel trims and take the O2 sensor out in the process.
We've replaced O2's both pre and after CAT by the thousands, and some had been driving around for a long, long time, with no other ill effects.

And as always, your mileage may vary from car to car.

OBDII is the same from car to car in a general sense, but the application of it from maker to maker is quite different.
What my experience has been (25+ years) might be different from someone else's.

 

[Gibson486]

Originally posted by: Zenmervolt

Originally posted by: Bartman39
Ok not sure where everyone gets their info but running with an O2 sensor either out of spec or not working at all is not good for any length of time... Reason... This is what tells the ECU how to trim the fuel system which directly affects the catalytic converter which is big bucks if left unattended...

It would take a _very_ long time for the lack of an O2 sensor to cause problems with the Catalytic converter. Any modern ECU will simply default to a "standard" fuel map when the O2 sensor readings are out of spec.

You'd need to drive for several years without an O2 sensor before you caused problems with the catalytic converter. In fact, the performance chip in my 951 completely disregards the signal from the O2 sensor and, shockingly enough, the car not only passes emissions with flying colors, but it also has managed to keep the catalytic converter healthy for the last 50,000 miles. (Original catalytic converter, the chips have been in the car at least 50,000 miles, car has 160,000+ miles on it right now.)

To the OP:

Fix the O2 sensor. It's pretty much guaranteed to be the problem and there's no reason not to fix it if you can afford it. Your father's worries really are unfounded.




ZV

Man.....I think I found out the reason why my catalytic converter (along with my charocol canister and evap suff) on my 01 Altima went south...I wish I would have known that earlier (the dealership told me that they could not find a problem with my check egine light, but at the time, it was under warrenty, so i think they just did not want to fix it). I always thought I had to replace the O2 sensor. Oh well....I am enjoying my new car.....

ZV, is a water pump a high failure part in an Altima?

 

[Gibson486]

Originally posted by: Zenmervolt

Originally posted by: Bartman39
Zenmervolt...

The 944 has only one O2 sensor

Might consider this is not a Toyota and a total different system... Do you work on every model and make of auto/truck every day...?

Do you lack the reading comprehension to understand that I pointed out that the 944 only has one to show that I understood that the systems were different?

Originally posted by: Bartman39

You overstate the risk by several orders of magnitude.

I`ll go the Geico caveman route "Uh WHAT...?"

If that's not simple enough for you to understand, I can't imagine how to make it any easier for you. You are overstating the risk to the catalytic converter. The OP would need to drive for tens of thousands of miles to do appreciable damage.

Originally posted by: Bartman39
This is like comparing apples to oranges but again what do I know...? Just a lowly mechanic that has no degree but started working on engines in 1972...?

Still doesn't make you right. There are many, many, many "mechanics" who have been working for decades that I wouldn't recommend even to someone I disliked, simply having been doing it for a long time doesn't mean you're right.

Driving the car for a month or two with the O2 sensor malfunctioning is not going to cause measurable damage to the catalytic converter. Is it less than optimal? Sure. But it's not the doomsday scenario you're making it out to be.

ZV

ZV is right....

My 01 Altima had the check engine light go on at 66K miles. It kept going on and off. At around 100k, the check engine light finally stopped completely. At 118K, it finally failed inspections due to a bad converter. The thing is the O2 sensor alone will not make you fail emmissions (all it has to do is return a result).....

 

[evident]

O2 sensor is important to giving you good gas milage and other important things, fix it.

 

[Zenmervolt]

Originally posted by: Gibson486
Man.....I think I found out the reason why my catalytic converter (along with my charocol canister and evap suff) on my 01 Altima went south...I wish I would have known that earlier (the dealership told me that they could not find a problem with my check egine light, but at the time, it was under warrenty, so i think they just did not want to fix it). I always thought I had to replace the O2 sensor. Oh well....I am enjoying my new car.....

ZV, is a water pump a high failure part in an Altima?

If the dealer said they couldn't figure it out, they couldn't figure it out. Dealerships actually love doing warranty work. Guaranteed money for them. It's the auto manufacturer that pays for the warranty repair, not the dealership. The dealer gets paid in full for the repair by the manufacturer.

The water pump isn't a high failure part on any car that I know of. Some designs have longer service lives than others, but typically they will all last at least as long as the timing belt.

ZV

 

[curtisjackson]

If it's the <nice try. Link deleted -DrPizza>, then you should replace it. If you smell something funny, like rotten eggs, while driving, then it's the O2 sensor.

I totally agree with this one! It can be cause from burning wires that is fried from your mulfunctioning sensor should replace it before its too late

 

[PhoKingGuy]

I totally agree with this one! It can be cause from burning wires that is fried from your mulfunctioning sensor should replace it before its too late

Spammer

 

[exdeath]

Fuel trim is just that, trim: a minor deviation. And it doesn't climb one way or the other indefinitely, it's capped by hard coded limits in the computer. If it's so far off that it's going to damage the cats, you're going to have other problems like rough running and stumbling, hesitation, stalling, etc. But that won't happen because those limits are well within the bounds of proper engine operation. Engine and parts safety isn't entrusted blindly and completely to sensors, there are hard absolute fail safes for that. The function of O2 sensors is primarily concerned with fine tuning of absolute minimum possible emissions; you'll get a check engine light tattling on you for potentially polluting the air long before there is a risk of component damage. Most computers know BS from a sensor when they see it.

And rotten egg smell is normal with cats on load transitions even when it's functioning normally. It has to do with the storage and release of excess sulfur in the fuel when the air flow and temperature through the cat changes.

 

[PhoKingGuy]

Fuel trim is just that, trim: a minor deviation. And it doesn't climb one way or the other indefinitely, it's capped by hard coded limits in the computer. If it's so far off that it's going to damage the cats, you're going to have other problems like rough running and stumbling, hesitation, etc.

And rotten egg smell is normal with cats on load transitions, it has to do with the storage and release of excess sulfur in the fuel when the air flow and temperature through the cat changes.

Check the post date out dude