rachel

Give P0171 Bank one oxygen sensor error message
We replaced that sensor, replaced the idle air control vale, PCV valve, MAF valve, took the front & center Catalytic converters off-they look like they could use to be replaced but even with them off it still idled down. The front 3 spark plugs were just replaced & are black already-??? What could this be???

Lexmex

Well messing around with the cats will just increase the problem. I don't have precats on my RX300, but I do have a Magnaflow high flow cat, and my emissions are very impressive given the cruddy gas here. With out the cats, I am referring to the main, big one, that can easily throw a P0420 low catalyst efficiency code, too.

Again, back to P0171, we'll run down the list:

1. Air intake (this could be one of the hoses)- in this case you may notice some idle problems and star ups
2. Fuel line pressure- fuel pump, fuel filter, fuel line injectors. I wouldn't be surprised here if one of the injectors is leaky
3. Injector blockage-
4. A/F sensors
5. MAF sensor
6. Engine coolant temperature sensor- there are two: one on the lower left (passenger) side of the radiator and another one near the airbox, water inlet and coolant hose that runs just on the right side (driver's side) of the engine block. (I'll try to remember to take photos today of these two) and the location of the water pump (though that is not related).

Lexmex

There is 1 engine coolant sensor and 2 water temperature switch connectors.

First one shown is on the lower passenger side of the radiator, circled in blue below. That is the Number 1 water temperature switch connector.

Second one shown is located right on the water inlet (behind the water inlet is the thermostat), circled in blue. That is the Number 2 water temperature switch connector.

Third photo shows this same area when I had my transmission out and the switch is circle in white. This is visible from the driver's side

Fourth photo shows the ECT sensor located on the passenger side from far away and circled in white.

Fifth photo shows the ECT sensor circled in white again in a close up shot.

rachel

I am suspecting he has put the o2 sensor in the wrong spot. Wouldnt that be a good laugh for everyone Where exactly is it located?

Lexmex

Happy to show you. First, there are two A/F sensors and 1 O2 sensor.

The Bank 1, Sensor 1 A/F sensor is located right behind the engine block here.

Lexmex

The Bank 2, Sensor 1 A/F sensor is located conveniently on the front of the engine block right here.

Lexmex

Bank 1, Sensor 2 is the O2 sensor, it is different than the A/F sensor in looks and performance and is located after the catalytic converter beneath the vehicle.

rachel

thank you. some of the inside of the caty has melted down & is fused all around that sensor-it looks fun. And he did put it in the wrong spot. A guy at autozone told him it was a different one, so I drove it with a 02 sensor in the a/f spot which was causing it to run rich & barely at all & has done a number on alot of parts I'm sure It is going to be a mess changing this one.

Rolexrx

Hi !
There seems to be another engine coolant temperature sensor linked to P0171: some call it ECT sensor (maybe ECT No. 3 in this case ? ), some call it simply water temperature sensor. The part number is 89422-35010 and this sensor is located at the right (timing belt) end of the engine, on the water outlet casting. This sensor affects the operation of the EFI, causing (among other symptoms) the P0171 code.
If anyone has pictures with the exact location of this sensor and / or instructions of how to change it, please post them, I believe they will be quite helpful.

murphysf

--
Hello

Is the Fourth and Fifth photo, the ECT sensor circled in white part number 89422-35010 8942235010 ?

Also is this the senor that would cause the P0128 ?

This morning my CEL came on with the above code.