Reader reads PO171, PO125, PO171 What do I do next?

98 2rz. So far the exhaust manifold has been replaced, new MAF sensor, New fuel filter, new coolant sensor (the one at the back of the engine by the fire wall) Smoke tested, no vaccuum leaks. Seems to maybe run better after the coolant sensor was changed, but the check light came back on within 5 miles, same old codes.What next?

 

Hmmmm

 

Man I hate to ask(but another member will)

OE MAF sensor?

also, I fell into AM hole with a CTS
Installed new AM one, 2.5 months later, determined (from help here) that new CTS failed had to install another under warranty

 

Oh yeah I forgot to say I replaced the thermostat.

It is not, I installed one recommended on this site, Hitachi

 

I’m not one to load parts cannon
But would at least bench test front O2

does she run hot?

 

Does not run hot. How do I bench test?

 

I have done the bench test
Just measuring Ohms (I forget the setting on mutlimeter though)
Lots of vids out there

 

The P0125 needs to be fixed first. The ECT temperature is used to signal the PCM that the motor is warmed up (closed loop mode) and can start using all of the other sensors to modify the fuel and spark. Until the PCM enters closed loop all of the outputs, spark timimg, fuel injection are read from the factory map.

 

Suggestions on how to fix it? I have replaced the thermostat and the ECT sensor, there are no leaks.I replaced the radiator some time ago, I believe it is in good shape.

 

I would verify that the PCM is or is not entering closed loop mode first. Different scan tools will show this different ways, some will just say CL or OL, others will say Mode: Open or Closed. If your scan tool shows an engine coolant temperature above 160* ish and she is still in open loop there is truly something odd happening. Most of the time the thermostat is defective and it is open just slightly.

From the 98 factory manual. Go throught the voltage checks.