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Jim
Grant has been working in the automotive industry for over twenty
years. In addition, Jim is an ASE Master Technician with advanced
L/1 certification. He works as manager and technician in his
family's automotive business in New Hampshire. He writes weekly
automotive consumer columns and is editor of an automotive newsletter
that is circulated throughout North America. |
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Jim Grant's Tech Tips
’97
01 VW Jetta, Oxygen Sensor Eate
Q:
I own an ‘01 VW Jetta and I had the oxygen sensors
replaced about 14 months ago. I have the same symptoms as
before. I’m only getting 200 miles out of a tank full
of gas, down from 325 miles out of a tank and the check
engine light is on. Why is this continuing to happen? My
luck is that it happened just after the 1 yr warranty expired.
I’m wondering why this keeps happening????? Is there
something else that needs to be repaired so this will not
continue? I have 36,000 miles on my Jetta.
Sanders
A:
The first
step, have the computer checked for the codes it is reporting.
There are nearly one hundred codes that can cause the check
engine light to come on in your vehicle. (Many of which
can cause a loss of gas mileage.) If the code is an oxygen
sensor code and the sensor has failed again, yeah there
is a question why? Bosch makes the oxygen sensors in your
vehicle and Bosch is known in the automotive industry for
making a very good product. That is why many other vehicle
manufacturers use Bosch product in their vehicles. There
was this Volvo that was ripping through oxygen sensors like
there was no tomorrow. On the third go around it was decided
that something else had to be going on, but the question
was just what? To keep it to a short novel it was found
that the coolant temperature sensor for the computer had
shifted out of range, it wasn’t broken, it just wasn’t
telling the truth. This little fib caused the computer to
provide just a little too much fuel. The oxygen sensors
could only handle this adjustment issue for so long before
they would cloud up and turn the check engine light on.
The computer, believing it was in control, would report
oxygen sensor problems. A replacement coolant temperature
sensor was the needed fix. Oxygen sensors do fail, but when
it becomes a repeat failure you have to start looking in
directions you just wouldn’t normally look in.
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