'94 Camry V6 XLE
Got my CEL read today at O'Reilly's. Came back with:

P0135 -- O2 Heater Circuit Bank 1 Sensor 1
P0115 -- Engine Coolant Temperature Circuit

Here are the symptoms of misbehavior on this car:

The dash temperature gauge reads very hot. The radiator, thermostat, and the coolant temperature gauge have been replaced. I brought the car to my mechanic to replace the water pump too, but he used the infrared temp. reader to determine that the cooling system was operating at the proper temperature. The problem is somewhere in the wiring.

Also, the engine tends to hesitate and chug (like the mix is off) when the engine is cold. Once the engine heats up it accelerates fine.

Obviously, I need to replace an O2 sensor. Where is bank 1, sensor 1? What do I do about the coolant temp circuit?

Thanks in advance!

 

The hesitation and chug could be caused by a bad engine computer coolant sensor. This sensor is different from the temp sensor for the dashboard gauge.

Wire colors for the engine computer sensor are green/black and brown.

Green/black wire goes directly to the computer located behind the glove box.

Brown connects to the MAF and TPS sensor, and EGR system then to the computer.

The O2 sensor is the first sensor on the exhaust system of the cylinder head nearest the firewall.

 

Well, I replaced the ECT sensor this morning and reset the CEL. The dash gauge is still reading hotter than a two dollar pistol, but we'll see how it starts up cold next time. So far the lights have not reappeared.

 

There is another coolant sensor that controls the radiator fans. Has 2 wires, blue/yellow and blue/white.

The sensor for the dash gauge has one wire, yellow/green going to the gauge. The gauge also has a ground wire running to it, brown.

Might check the brown wire has a good ground.

And that there is good continuity in the yellow/green wire between the sensor and gauge.

 

This sensor is different from the temp sensor for the dashboard gauge.