justdefiant wrote:I actually extended the wiring to the o2 sensor by splicing some wire in. Also my car is a 1999 and it is supercharged, only running 4 psi, as only have 91 octane where I live.
Do I have to go to a dealer to get a better scan, or will the same tool my friend has that kicked out the 125 code work?
If your friends scantool is just a small hand held code reader it probably won't help you much with diagnosing the code, it will just tell you what the code is, but if you are able to watch & read live data with it, that's what you need. You should start with reading the voltages for both Bank 1 Sensor 1 & Bank 2 Sensor 1 to make sure they are working properly. I would assume because of your location your car is NOT a California spec car, so this is what Toyota has in their service manual for diagnosing the P0125 code on a NON California spec car:
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 of the 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 whereby 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: < 0.45 V).
When the air−fuel ratio is RICHER than the stoichiometric air−fuel ratio the oxygen concentration in the exhaust
gas is reduced and the oxygen sensor informs the ECM of the RICH condition (large electromotive
force: > 0.45 V). 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.
The heated oxygen sensors include a heater which heats the Zirconia element. The heater is controlled by
the ECM. When the intake air volume is low (the temperature of the exhaust gas is low) current flows to the
heater to heat the sensor for accurate oxygen concentration detection.
If your friends scantool will read live data and you want to attempt to diagnose the problem yourself; PM me your email address and I will send you the complete diagnosis proceedure right out of the book from Toyota. It's about 4 pages long and very self explanitory, but without a proper scantool it won't help much. Also, this proceedure is for a factory N/A car, but that shouldn't matter. You would diagnose the code the same way even with the supercharger. I hope this helps, if all else fails, take it into your local dealer and at least you'll be well informed on the issue so you can make sure it's fixed correctly.