Bumbobee

Hey guys,

I had the CEL come on and off before, and now it's pretty much on solid the whole time. I took my car in and my mechanic says it might be vacuum leak so he checked with smoke for any leaks and all is well. He said that the codes probably mean that the upper air/fuel ratio sensors have to be replaced.

He said both of the uppers need to be replaced.

Do you guys think that's the issue?

Car feels sluggish during acceleration, not extreme, but more than I remember it being. Also the gas economy is probably like 10 % less than what it used to be.

I've cleaned the MAF sensor so I don't think it is that.

Car has 262,000 km on it right now.

PuReChaos

I wouldn't be so quick to condemn the AF sensors. It would be interesting to see what your fuel trim numbers were showing.

Consider the other half of the equation. You might have low fuel pressure. Theres a number of things that could cause this, weak fuel pump, clogged/dirty fuel filter, fuel pressure regulator, etc.

I dont know if your mechanic has a good scan tool or not, but toyota does have active tests that they could perform using techstream to verify if it actually is the sensors or not. Then again this is a 10+ year old car and the sensor costs about what toyota would charge to diagnose the problem.

Bumbobee

Fuel filter was replaced last year. Not sure about the other things. Safe to say that with that age and mileage and extreme commuting in the GTA, sensors should be changed?

How many sensors are there in total? 2 upper and 2 lower?

Bumbobee

Anyone know how many sensors there are in total? Kind of want to buy them and have the whole shipping process started.

PuReChaos

Not sure about the Canada one, but just asked my coworker and he says there are 3, two air fuel and one heated oxygen sensor.

I would have thought similar to you that there would be two air fuel and two oxygen, however he claimed that wasn't the case. Maybe someone else knows?

Bumbobee

I think Canada models and US models are the same. I googled some engine diagrams and it seems like 3 (2 upstream 1 downstream) but I just want to be sure.

Bumbobee

Ordered 3 sensors from rockauto

2001 LEXUS ES300 3.0L V6

DENSO 2344137 (234-4137) Oxygen Sensor CAD$ 55.38 CAD$ 0.00 x1 CAD$ 55.38

DENSO 2349021 (234-9021) Oxygen Sensor CAD$ 122.97 CAD$ 0.00 x2 CAD$ 245.94

Can these be put in DIY or I need a mechanic? How hard is it?

PuReChaos

I'd classify it as DIY-able. Obviously since you'll be around the exhaust, I suggest doing this while the engine is cold. You'll need to lift the front of the car to get the sensor on the back bank and honestly its just a lack of room to work with that makes it "difficult." The front one will be a piece of cake. You'll want to buy an oxygen sensor socket. If you care for the torque specification its 32ftlbs.

If you have a digital multimeter, you can test your sensors while your at it. The AF sensors before the cat should read .08-1.4 ohms when the engine is cold and 1.8-3.2 ohms when hot. The oxygen sensor should be 11-16 ohms when the engine is cold and 23-32 ohms when hot.

01LEXPL

iTrader: (10)

It depends... They may be in there really good hot/col temps seem to seize these up really good, especially on a 14yo vehicle... Try it, if not return the socket and take it to a shop, this way your out your time only!