1996 Lexus ES 300: Oxygen Sensor Fixed
January 31, 2013
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