Oxygen Sensor Fixed - 1996 Lexus ES 300 Long-Term Road Test

1996 Lexus ES 300 Long Term Road Test

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1996 Lexus ES 300: Oxygen Sensor Fixed

January 31, 2013

1996 Lexus ES 300

On a road trip to Death Valley, the dreaded check engine light (CEL) came on. When we came back, we took the car to Pep Boys and they read the code for free: P0135, which meant that the oxygen sensor in "bank 1" was malfunctioning. It was surprising to learn that something was wrong with the car, since it still seemed to be running fine.

Even though a car seems to be behaving normally, experts say a faulty oxygen sensor can cut the fuel economy by 40 percent. Sure enough, when we checked our fuel records for the driving we did while the CEL was on, our fuel economy dropped from about 27 mpg to about 24 mpg.

We considered the DIY route to fixing the O2 sensor but after a little researched we learned the faulty sensor was in the rear of the engine and difficult to reach. Instead, we took the Lexus to Overseas Garage, in Long Beach, Calif. There, the mechanic told us that the new sensor would cost $117, plus $144 in labor for a total of $261.

Apparently, the V6 engine in our Lexus, has one sensor in each exhaust manifold and one after the catalytic converter. The sensors simply screw into place, but reaching them can be a problem for do-it-yourselfers. Additionally, we learned that, since the exhaust subjects the sensor to extreme heat, it can "seize" or become frozen in place and be tough to unscrew. A new sensor comes with anti-seize compound to apply to the threads, but the compound should never be put on the sensor itself.

While many people opt to simply ignore the CEL, we wanted to do our part to cutting emissions and save money on gas. In the long run, we think we'll come out ahead. Driving back from the garage, it was a relief not to stare at the glowing check engine light. This made us realize that fixing such a problem provides another benefit: peace of mind.

Philip Reed, Senior Consumer Advice Editor, @ 152,834 miles


  • fordson1 fordson1 Posts:

    This is a $50-$60 part, even if you get the Denso OEM one. They all say that it's tough to get to, but...you can at least try yourself first, before concluding it's too tough. Even if you had to buy the O2 sensor socket, this is potentially a $75 repair. Even if you end up having a shop do it, you could still have avoided paying double for the part itself. Philip, you people are missing the boat on all of these easy repairs - sooner or later, this car is going to need an expensive, tough-to-perform repair that you will HAVE to take it in for, and you are going to be way behind the curve on your cost per mile.

  • noburgers_ noburgers_ Posts:

    I agree, fordson1, all repairs that are reasonably DIY should be tried, then seek professional advice if it can't be done. If I could reach it, I'd see if it could come undone. If seized, take it in. I wouldn't even buy the part unless I knew it could be undone. But to their credit, they did do some research to see if it made sense to try doing this and thought it was best to get it done at the shop. One good point from this issue is the affect on fuel economy--at approximately 10% loss of mileage, it would take $2600 in gas, or 2600/$4gal = 650 gallons at 24mpg = 15600 miles of driving to pay back--approximately one year of driving.

  • fordson1 fordson1 Posts:

    I would buy the part Once I get the car up in the air, get my tools out, get dirty and get the part loosened, I don't want to have to tighten it up again, then come back and do all that crap over again when I get the part into my hands. If you find you can't get the part out - if you have a good shop you have a relationship with, you can supply parts to have them do the work.

  • bassracerx bassracerx Posts:

    im assuming the quote to get it done at pep boys was more? what was it? did they have a long wait? did you have to get the fleet manager to authorize it?

  • eric_l eric_l Posts:

    It is "difficult to reach" because it requires accessing the sensor from under the car. But then, Edmunds has their own lift! This would have made a great DIY writeup using your own lift for something other than suspension pictures.

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