Intermittant Cel And Trac On/off - P1153

[SBURGE]

Hi -

Some quick history: I have '99 ES300 with 67,700mi. Had the engine oil sludge issue which had symptoms of CEL and Trac on lights on intermittantly and blue smoke from exhaust. This was fixed by Lexus about 4 years ago.

About 10 months ago up until recently, the CEL and Trac lights will go on for a period of time (say a few days every two months) and then will go back out. Often it seems to happen when there is a change in weather or if there is high humidity (as in raining alot!). I took it to autozone and they detected P1153 - Bank 2 fuel control shifted lean (bank2 sensor1).

My questions are this:

1. could this be related to the oil sludge issue?

2. why would the lights go on and off if the sensor was faulty. wouldnt the lights just stay on?

3. how does this affect the performance of the car besides poor fuel economy. Shifted lean means less oxygen during combustion, right?

4. is it imperative that I get it fixed or should I wait until the lights stay on always?

Thanks in advance! I appreciate it!

[steviej]

My questions are this:

1. could this be related to the oil sludge issue?

2. why would the lights go on and off if the sensor was faulty. wouldnt the lights just stay on?

3. how does this affect the performance of the car besides poor fuel economy. Shifted lean means less oxygen during combustion, right?

4. is it imperative that I get it fixed or should I wait until the lights stay on always?

Thanks in advance! I appreciate it!

1. probably not.

2. the lights come on when the signal from the AF sensor, in this case bank 2 sensor 1, to the ECU is outside of acceptable limits. It may not always send the same signal. If the sensor were faulty, then yes, I would expect the lights to constantly be lit. However, the sensor may not be faulty, but what we call, lazy. It all comes down to what the sensor interprets and the signal that is created.

3. it can create a situation where there is unburned fuel in the mix. The signal calls for more fuel to be added. More unburned fuel can pass through the cylinder and into the exhaust. Once in the extreme heat of the catalytic converter it is burned there instead. This will lead to a premature death of the cat. This piece of equipment is much more expensive than a sensor.

4. get it fixed since you have been experiencing this for 10 months.

Bank 2 sensor 1 is the easiest to get at. You can actually see it when standing in front of the car. It is in the exhaust between the manifold and the cat. Look between the radiator and the front of the engine, looks like a spark plug with a wire coming out of the back. Follow the wire back to its connector and unclip it carefully. Apply a little liquid wrench to the threads and wait. Apply some more and wait. Allow the liquid wrench to seap in. Use an O2 socket to get the old one out and to insert the new one.

AF or O2 sensors can be had on the interent for less money than at the stealership.

(try www.sparkplugs.com or www.oxygensensors.com), Expect to pay about $200 for a Denso sensor.

steviej

Good luck.

steviej