P2000 NOx Trap Efficiency Below Threshold (Bank
1)This code usually indicates a faulty oxygen
sensor(s). However, in some instances it can also be used for a faulty
catalytic converter as well, since the O2 sensors are located on the
exhaust system along with the cat. converter(s). You should check your O2 sensors before replacing the catalytic converter. Here is a guide on checking these sensors.
All engines run on a optimum fuel to air mixture called "stokiometric" which
means chemically balanced. This balanced fuel to air ratio is 14.7 to 1, 14.7
parts air to 1 part fuel. The oxygen sensor is created using the active chemical
such as zirconium, electrochemical (also known as Galvanic), infrared,
ultrasonic and very recently laser. When a lean mixture code is detected by you
or a technician the first tendency is to replace the oxygen sensor. The best way
to check the operation of the sensor is to run a simple test. No matter if your
engines oxygen sensor has one wire or four there is only one sensing wire that
feedbacks information to the PCM. To find this wire you will need a
. If a trouble code is present that pertains to a oxygen heater sensor
failure, replace the sensor to repair the problem. A oxygen sensor must be warm
before it will operate properly.
If a malfunction exists with related
components such as an
engine vacuum leak
do not perform this test. The
to designed to operate within a particular range, if this range is
exceeded the sensor will give the appearance that it has failed.
SENSOR TEST PROCEDURE---
- Step 1 - Once the oxygen sensor sensing wire has been
located connect a volt meter to the feedback wire and ground. Select the millivolt
operation on the meter.
- Step 2 - Next, start and
run the engine at idle until warm (about 15 minutes). Observe the voltmeter, it
should bounce slightly at whatever voltage the sensor is centered at (about 150
- Step 3 - Continue to observe
the meter and have a helper rap the throttle. The meter should drop for a split
second as the mixture leans out in the first milliseconds of the throttle bore
being opened. Then quickly rise for a spit second as the throttle closes and
the mixture richens. The volt meter should stabilize at the original operating voltage
when the engine returns to idle.
Remember, if the sensor fails this test, replace it but if it passes, replace the Catalytic converter...
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