2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem

"Mark G. Meyers" wrote in message

> Hi,
> I am a bit shocked at seeing what they want in diagnosing my car at the
> shop. It shows $310 parts must be ordered, for a front oxygen sensor.
>
> The codes being produced are P0125, P0171, and B151. I haven't found such
> a
> thing as B151 anywhere.
>
> If I investigated this right:
> P0125: Insufficient coolant temp for closed-loop fuel control
> P0171: System too lean
>
> What they are saying at this shop is that they need to clean the mass air
> flow sensor, and replace the front oxygen sensor. I asked about doing the
> cleaning now, and was told it would work better to do both at the same
> time.
>
> My first reaction is that the price of the part seems awfully high. Any
> ideas as to what it is or where one should look next?
>
> TIA -
> Mark
>
P0125 and P171 both point to Bank 1 Sensor 1, and perhaps a dirty MAF
sensor. Bank 1 Sensor 1 is the O2 sensor that is sticking out of the
exhaust manifold. You can replace it yourself by unplugging it, unscrewing
it from the manifold, installing the replacement sensor, and plugging it in.
The gotcha is if the sensor is rusted and strips the manifold when you
remove it, in which case you would need a new exhaust manifold. You can
install a less-expensive aftermarket O2 sensor, but if you go this route,
make sure you get one with the factory plug so you don't have to cut and
splice wires. I've heard of spotty results with aftermarket emissions parts
so I prefer OEM.

You can clean the MAF sensor, which is installed in the engine air filter
housing by unplugging it, removing it from the air filter housing, and
spraying some brake cleaner in and letting any grit or dirt drip out, then
re-installing the sensor.

I'm not sure what B151 is, but it refers to a body-related system like the
seat belt system, supplemental restraint system (airbags), ABS, etc.
--

Ray O
(correct punctuation to reply)
 >> Stay informed about: 2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem 

Thanks, I'll check with a local garage.

Cheers -
Mark
 >> Stay informed about: 2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem 

Thanks for all of that. In fact, I don't know what the difference between
being one bank and another bank means, but I've worked with exhaust headers
before, and I can see in aftermarket parts, there are $30 ones, and $60-80
ones. And I'll check Toyota parts. Its running lean right now, and the
engine shouldn't take that for long.

Much appreciated -
Mark



"Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message

>
> "Mark G. Meyers" wrote in message
>
> > Hi,
> > I am a bit shocked at seeing what they want in diagnosing my car at the
> > shop. It shows $310 parts must be ordered, for a front oxygen sensor.
> >
> > The codes being produced are P0125, P0171, and B151. I haven't found
such
> > a
> > thing as B151 anywhere.
> >
> > If I investigated this right:
> > P0125: Insufficient coolant temp for closed-loop fuel control
> > P0171: System too lean
> >
> > What they are saying at this shop is that they need to clean the mass
air
> > flow sensor, and replace the front oxygen sensor. I asked about doing
the
> > cleaning now, and was told it would work better to do both at the same
> > time.
> >
> > My first reaction is that the price of the part seems awfully high. Any
> > ideas as to what it is or where one should look next?
> >
> > TIA -
> > Mark
> >
> P0125 and P171 both point to Bank 1 Sensor 1, and perhaps a dirty MAF
> sensor. Bank 1 Sensor 1 is the O2 sensor that is sticking out of the
> exhaust manifold. You can replace it yourself by unplugging it,
unscrewing
> it from the manifold, installing the replacement sensor, and plugging it
in.
> The gotcha is if the sensor is rusted and strips the manifold when you
> remove it, in which case you would need a new exhaust manifold. You can
> install a less-expensive aftermarket O2 sensor, but if you go this route,
> make sure you get one with the factory plug so you don't have to cut and
> splice wires. I've heard of spotty results with aftermarket emissions
parts
> so I prefer OEM.
>
> You can clean the MAF sensor, which is installed in the engine air filter
> housing by unplugging it, removing it from the air filter housing, and
> spraying some brake cleaner in and letting any grit or dirt drip out, then
> re-installing the sensor.
>
> I'm not sure what B151 is, but it refers to a body-related system like the
> seat belt system, supplemental restraint system (airbags), ABS, etc.
> --
>
> Ray O
> (correct punctuation to reply)
>
>
 >> Stay informed about: 2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem 

Here are the OBD II Codes,
http://autorepair.about.com/od/obdcodedatabase/a/OBD_1996_year.htm

Try replacing B151 with P0151 (I'm thinking Po is blurred together to give
you a B (the actual code is P-Zero, not P-Oh)), and you get an error of Bank
2, Sensor 1. Since you haven't got an engine that even has a Bank 2, I'd
clear all codes and drive until you get a code again.

Bank 1 and Bank 2 refer to a V-engine, V-6 or V-8, etc., and you have an
inline 4, so you only have a Bank 1. Bank 1 is the cylinder bank that
contains the #1 Piston.).

My guess is that the P0125 code is the real problem. The OBD II system is
pretty good, but there are false codes that can crop up. There are also
instances where an upstream code can cause a downstream sensor to report
that it is out of range. For example, if the coolant temp is not correct,
the downstream sensor (O2) might report that the mixture it is monitoring is
not within the expected range.

IF your car has no driveability issues, I would suggest that it is safe to
erase the codes you see today, and wait for the Check light to come up
again. The subsequent occurance should be relatively soon, and should
consist of a code you have written down already. This code should be pretty
close to the actual problem.

RayO, also in this thread, should have a good test procedure to check the
usual suspects.





"Mark G. Meyers" wrote in message

> Hi,
> I am a bit shocked at seeing what they want in diagnosing my car at the
> shop. It shows $310 parts must be ordered, for a front oxygen sensor.
>
> The codes being produced are P0125, P0171, and B151. I haven't found such
> a
> thing as B151 anywhere.
>
> If I investigated this right:
> P0125: Insufficient coolant temp for closed-loop fuel control
> P0171: System too lean
>
> What they are saying at this shop is that they need to clean the mass air
> flow sensor, and replace the front oxygen sensor. I asked about doing the
> cleaning now, and was told it would work better to do both at the same
> time.
>
> My first reaction is that the price of the part seems awfully high. Any
> ideas as to what it is or where one should look next?
>
> TIA -
> Mark
>
>
 >> Stay informed about: 2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem 

"Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message

>
> I'm not sure what B151 is, but it refers to a body-related system like the
> seat belt system, supplemental restraint system (airbags), ABS, etc.


Good call, Ray, I missed that.

I'm thinking penmenship is the problem here, Po (which should be P0) is
bleeding together to become B, this would make the code to be P0151, which
is an error unless they stuff a V6 into a Corolla ...

Even if the B was correct, there are not enough digits in the code, B151,
given.
 >> Stay informed about: 2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem 

Probably check/fix the coolant temperature sensor first. It's a ~$20
part.

The OBD-II may not be very intelligent to disable setting the oxygen
sensor codes while temperature puts it out of closed loop operations.

So before you spend on the oxygen sensor, do a check on the coolant
sensor:

rockauto.com ~$16:
http://info.rockauto.com/Airtex/Detail.html?5S1491.jpg



On Oct 2, 1:56 pm, "Mark G. Meyers"
wrote:
> Hi,
> I am a bit shocked at seeing what they want in diagnosing my car at the
> shop.  It shows $310 parts must be ordered, for a front oxygen sensor.
>
> The codes being produced are P0125, P0171, and B151.  I haven't found such a
> thing as B151 anywhere.
>
> If I investigated this right:
> P0125: Insufficient coolant temp for closed-loop fuel control
> P0171: System too lean
>
> What they are saying at this shop is that they need to clean the mass air
> flow sensor, and replace the front oxygen sensor.  I asked about doing the
> cleaning now, and was told it would work better to do both at the same time.
>
> My first reaction is that the price of the part seems awfully high. Any
> ideas as to what it is or where one should look next?
>
> TIA -
> Mark
 >> Stay informed about: 2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem 

"Mark G. Meyers" wrote in message

> Thanks for all of that. In fact, I don't know what the difference between
> being one bank and another bank means, but I've worked with exhaust
> headers
> before, and I can see in aftermarket parts, there are $30 ones, and $60-80
> ones. And I'll check Toyota parts. Its running lean right now, and the
> engine shouldn't take that for long.
>
> Much appreciated -
> Mark
>

Bank 1 refers to the cylinder bank that contains cylinder #1 and Bank 2
refers to the bank that does not contain cylinder #1. V6, V8, V12, and
engines with horizontally opposed cylinder banks like Subarus and Porsches
have 2 banks of cylinders. Engines with an inline cylinder configuration
like your Corolla's inline 4 have only 1 bank of cylinders so your engine
does not have a Bank2.

Sensor 1 refers to the sensor that measures the amount of oxygen, or O2 in
the exhaust gas as as it exits the engine, before the gas passes through the
catalytic converter. A "rich" condition means that there is too much fuel
in relation to the amount of air entering the engine, and a "lean" condition
means that there is too little fuel being injected in relation to the amount
of air entering the engine. Sensor #1 monitors the amount of oxygen (O2) in
the exhaust gas, and based on the sensor reading, the car's engine
electronic control module (ECM) adjusts fuel mixture by adjusting how long
the injector is open. When the engine and emisisons sytem are warmed up,
the amount of O2 will fluctuate and so the voltage from the O2 sensor #1
will also fluctuate.

Sensor #2 refers to the sensor that measure the amount of O2 in the exhaust
gas after it has passed through the catalytic converter. After the exhast
gas passes through the catalytic converter, the amount of O2 in the exhaust
should be evened out and so the voltage from O2 sensor #2 should not
fluctuate as much.

If the signal from sensor #2 is fluctuating like the signal from Sensor #1,
that means that the catalyhtic converter is not working properly and a check
engine light is illuminated.


--

Ray O
(correct punctuation to reply)
 >> Stay informed about: 2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem 

"Jeff Strickland" wrote in message

>
> "Ray O" <rokigawaATtristarassociatesDOTcom> wrote in message
>
>>
>> I'm not sure what B151 is, but it refers to a body-related system like
>> the seat belt system, supplemental restraint system (airbags), ABS, etc.
>
>
> Good call, Ray, I missed that.
>
> I'm thinking penmenship is the problem here, Po (which should be P0) is
> bleeding together to become B, this would make the code to be P0151, which
> is an error unless they stuff a V6 into a Corolla ...
>
> Even if the B was correct, there are not enough digits in the code, B151,
> given.
>

I suspect that if the OP fixes the root cause, he can ignore the B151.
--

Ray O
(correct punctuation to reply)
 >> Stay informed about: 2001 Corolla Coolant Temp/Fuel Control/Oxygen Sensor Problem