toyotas confusing P0125

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#1
I am confused-
toyota P0125* and why is O2 sensor involved?
anyone have OEM trouble tree or can explain -

*P0125= coolant temp
 

billr

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#2
Do you have a different definition of P0125 than shown on the link here; why are you saying the O2 sensor is involved?
 
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#3
The way that I read it is that PO125 code is set when a lean condition in recorded and the mil light will come on. This information is on a 2000 toyota camry. They want you to check the heated oxygen sensor to make sure the heated oxygen sensor is not bad and working properly and not stuck in a lean condition and causing the code. If it is good then the lean condition is caused by something else up the line. They also say that PO125 is set when it runs out of gas causing the lean condition. This is from a non california car. I don't know what year you are working on. Maybe what you are working on is saying that the ECT is not up to temperature and you don't have heated oxygen sensors and it is running in open loop because of it. Just my $.02 worth.
 
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#4
I found this with Google...

Many codes, one problem.

Oxygen sensor failures are common to all cars not just Toyotas. But Toyotas present different codes that you might not expect for this common problem.

When a car has the 300 dollar oxygen sensor (California emissions) we call it the air fuel ratio sensor. Check with Toyota dealer by VIN number to verify which type you have. An air fuel ratio sensor is not interchangeable with a regular oxygen sensor even though they look the same.

P0171 System Too Lean. This code will set when an air fuel ratio sensor gets lazy.

P0125 Insufficient Coolant Temperature For Closed Loop. Sounds like a bad thermostat right? No, on Toyotas its our air fuel ratio sensor taking too long to get active.

P1135 Air Fuel Ratio Sensor (Bank 1 Sensor 1) Heater Circuit Malfunction. The heater in the air fuel ratio sensor is drawing too much or too little current.

Amazon sells the Bosch 13733 air fuel ratio sensor for about 113 dollars which is the lowest price I have been able to find anywhere. This sensor works well on
 
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#5
It also says that there are Variation to the Code PO 125.

It says on some models, Toyota does not adhere to the SAE definition for DTC125 which is related to the ECT.

I guess that is why the oxygen sensor is in the diagnosis of some Toyota cars and not of some other Toyota's.

Nothing like trying to make it simple and less confusing!!
 

billr

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#6
Kev didn't say what MY, but since it is a "P" type code, I assume it is late enough to be OBD2. I would think it would be illegal for Toyota to deviate from standard for the basic codes!
 
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#7
1997 corolla ....


And Billr I agree with you 100% - think of how the testing 'police' allow you slack... should be worse for dealers manufacturers. .... But my dislike of testing for profit is well known

Danica's post showed the issue - wondering if anyone can bring me up to speed 'teach me' or a troubleshooting tree?
 
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#9
Finally got it to come up somehow. This trouble chart is for a 1997 toyota corolla. Different charts for different years and models.
 

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#10
thats it -- THANKS

B1S1 - I will bet that it MUST be OEM only....

I post so many of these trouble trees WHY do they make them proprietary?? hard to find ?
and ALWAYS step 1 connect tech II et al-

ths BS got to me! emission testing???