JerryWatts

1999 RX300. Was Getting CEL codes:

P1125 - Bad Coolant Temp Sensor.
P1135 - B1P1 O2 Sensor
P1155 - B2P1 O2 Sensor.

Replaced the Coolant Temp sensor. That code went away.

Replaced Both upstream O2 sensors. Those codes went away.

Now getting P0125. Insufficient temp for closed loop (yadda yadda yadda). DID NOT get that code until after replacing the O2 sensors.

Im planning on replacing the thermostat. Any other thoughts?

carguy07

What brand sensors did you use?

salimshah

What does the temp gauge show after 15-20 min of driving?

Salim

JerryWatts

I used Denso Oxygen sensors

JerryWatts

No numbers on the gauge. I'd say about 1/4 or 1/3 of the range of movement.

salimshah

Is the vehicle new to you? Just trying to see if it is different from past.
Typically it should be around 1/2 ... mine was a tad below 1/2 but you can approximate it to be 1/2. Typical life of thermostat is about 10yrs. Make sure you get the gasket forming material rated for temp and coolant along with the thermostat.

Salim

Htony

I'd try to reset everything by disconnecting battery, let ECU learn again. O2 sensors give proper voltage reading? Temp. sensor exact replacement?