How to Fix Your Car's Oxygen Sensor Fix Now or It Will Cost More in the Long Run
Published: 02/11/2013 - by Philip Reed, Senior Consumer Advice Editor If your
car's "Check Engine" light is glaring at you, it's probably because the oxygen
sensor is malfunctioning. That's right, the oxygen sensor. It's a little device
that's a mystery for most drivers but its misbehavior is the problem that most
commonly triggers a Check Engine light, according to , which sells an automotive
diagnostic tool and provides repair information. The oxygen sensor unseats the
formerly most common Check Engine light culprit: a loose gas cap. There are
fewer reports of that problem because savvy motorists have learned to fix it
themselves and consumers now buy new cars with capless gas tanks. But don't
despair. Replacing your car oxygen sensor will keep you from wasting money by
burning extra gas, and the repair isn't horribly expensive. We know this
firsthand. We had to replace the O2 sensor on our 1996 Lexus ES 300, the subject
of our Debt-Free Car project, and it wasn't as much of a hassle or expense as we
had feared. After the dreaded Check Engine light appeared in our Lexus, we
plugged the CarMD device into the car's computer to read the error code. In our
case, the code was 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, a faulty oxygen sensor will cause the engine to start
"gulping down gas," says Kristin Brocoff, director of corporate communications
for . She says this problem can cause up to a 40 percent reduction in fuel
economy. Sure enough, when we checked our fuel record for the driving we did
while the Check Engine light was on autel
maxisys pro ms908p, our mpg had taken a hit. The oxygen sensor, developed in
the early 1980s, is an essential part of the car's emissions control system,
says John Nielsen, director of engineering and repair for the American
Automobile Association (AAA). The sensor is about the size and shape of a spark
plug and protrudes into the car engine's exhaust stream. It determines if there
is a lot or a little oxygen in the exhaust, so the engine can make adjustments
to the amount of fuel being used in the engine to run at maximum efficiency.
Oxygen sensors in older cars fail for a variety of reasons, according to Bosch,
a leading manufacturer of auto components. In some cases, sensors are fouled by
gasoline additives or oil from worn engines. Newer oxygen sensors can last
100,000 miles if conditions are right, but often problems occur sooner. After we
plugged CarMD's diagnostic device into the Lexus' onboard computer port, we
connected it to our desktop computer. It accessed a database of information
about this engine code and how to have it repaired. Among other things, the
report included an average estimate just to buy a new oxygen sensor: $. At the
first sight of a Check Engine light, most owners of new cars that are still
under the factory warranty would simply make a beeline for the dealership's
service bay. But car owners on a budget might want to go the do-it-yourself
diagnosis route to save money. By using the CarMD device, or any engine code
reader, drivers can learn what the problem is, and the skill level required to
fix it, before attempting the task. Modern cars have two to four oxygen sensors,
Nielsen says. A V6 engine, such as the one 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, since the exhaust subjects the sensor to extreme heat, it can
"seize" (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. Nielsen says that while a code reader might
indicate that the problem is the car oxygen sensor, there are other problems
that can trigger the identical code - a disconnected vacuum hose will do it, for
example. As a first step, a car owner can look under the hood to see if there
are any wires or hoses disconnected, Nielsen says. In some cases, a wire leading
to the oxygen sensor could be broken or burned out. If nothing obvious is
visibly awry, it's time to go to what Nielsen calls "a trusted mechanic."
Reputable garages use an expensive diagnostic machine called a scan tool - not
to be confused with an inexpensive code reader - that can watch the operation of
the engine in real time and see if the oxygen sensor is actually the problem.
"Most motorists would be well served to find a shop that they trust and take
their car there for all oil changes and tire rotations," Nielsen suggests.
"Then, when they have a problem with something like an oxygen sensor, they trust
what the mechanic is saying rather than thinking that they're trying to rip you
off." In our case, we learned that the faulty O2 sensor was in the rear of the
engine and difficult to reach autel
ms509, so the fix seemed above our skill level. Instead, we took the Lexus
to Overseas Garage, in Long Beach, California. There, the mechanic told us that
the new sensor would cost $117, plus $144 in labor for a total of $261. This was
close to the $246 average cost cited by CarMD'sBrocoff. While many people opt to
simply ignore "Check Engine" lights, Brocoff says this can cause bigger, more
costly problems later. "So the problem you could have fixed for a few hundred
dollars turns into a repair of the catalytic converter, which would be over a
thousand." 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.
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