6G Celicas Forums

Hi i was wondering if anyone can help me with this problem.
ive got the p0125 code problem and ive taken the steps that i know of to fix it and nothing works.
i replaced the cooling temp sensor and i have checked all of the other sensors and they are working properly.
any help Will be appreciated.
thanks
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how about replacing the thermostat?

i dunno, i just read some info on that code, give you more but kid is going to bed. There is something to do with the O2 sensor. Its in the BGB stuff. Im sure its floating around somewhere....nevermind here is what it says....
CIRCUIT DESCRIPTION
To obtain a high purification rate for the CO, HC and NOx components of the exhaust gas, a three-way
catalytic converter is used, but for the most efficient use three-way catalytic converter, the air-fuel ratio must
be precisely controlled so that it is always close to the stoichiometric air-fuel ratio.
The oxygen sensor has the characteristic where by its output voltage changes suddenly in the vicinity of the
stoichiometric air-fuel ratio. This characteristic is used to detect the oxygen concentration in the exhaust
gas and provide feedback to the computer for control of the air-fuel ratio.
When the air-fuel ratio becomes LEAN, the oxygen concentration in the exhaust increases and the oxygen
sensor informs the ECM of the LEAN condition (small electromotive force: 0 V).
When the air-fuel ratio is RICHER than the stoichiometric air-fuel ratio the oxygen concentration in the exhaust
gas in reduced and the oxygen sensor informs the ECM of the RICH condition (large electromotive
force: 1V).
The ECM judges by the electromotive force from the oxygen sensor whether the air-fuel ratio is RICH or
LEAN and controls the injection time accordingly. However, if malfunction of the oxygen sensor causes output
of abnormal electromotive force, the ECM is unable to perform accurate air-fuel ratio control.
DTC No. DTC Detecting Condition Trouble Area
P0125
After the engine is warmed up, oxygen sensor output does not
indicate RICH even once when conditions (a), (b), © and (d)
continue for at least 1.5 min.
(a) Engine speed: 1,500 rpm or more
(b) Vehicle speed: 40 - 100 km/h (25 - 62 mph)
© Throttle valve is opened
(d) Engine has been started for at least 140 sec.

Open or short in oxygen sensor circuit

Oxygen sensor (bank 1 sensor 1)
HINT:
After confirming DTC P0125 use the OBD II scan tool or TOYOTA hand-held tester to confirm voltage output
of oxygen sensor from "CURRENT DATA".
If voltage output of oxygen sensor is 0 V, oxygen sensor circuit may be open or short
INSPECTION PROCEDURE
1 Connect the OBD II scan tool or TOYOTA hand-held tester and read value for
voltage output of oxygen sensor (bank 1 sensor 1).
PREPARATION:
(a) Connect the OBD II scan tool or TOYOTA hand-held tester to the DLC3.
(b) Warm up engine to normal operating temperature.
CHECK:
Read voltage output of oxygen sensor (bank 1 sensor 1) when engine is suddenly raced.
HINT:
Perform quick racing to 4,000 rpm 3 times using accelerator pedal.
OK:
Oxygen sensor output a RICH signal (0.45 V or more) at least once.
OK Check and replace ECM (See page IN-28 ).
NG
DI-42
DIAGNOSTICS - ENGINE (7A-FE)
1996 CELICA (RM443U)
2 Check for open and short in harness and connector between ECM and oxygen
sensor (bank 1 sensor 1) (See page IN-28 ).
NG Repair or replace harness or connector.
OK
Replace oxygen sensor (bank 1 sensor 1).

I checked the thermostat and its working properly.

thanks man but could you just make a list of what i have to do lol

Just PM me your e-mail and I'll send you the pages. But your pretty much making sure your 02 sensor is working properly.

just replace the o2 sensor... its not that expensive and it ALWAYS helps... esp w/ gas mileage... if that doesn't fix it then there is a short in o2 sensor line or ECU.

Did you ever fix it? Because i have the same problem now.