My Jeep Liberty Has a 3.7 L V6, it has problems starting. A code popped up that was P0325? What does this code mean?
CARB (California Air Resources Board)
has a consistent policy regarding monitoring knock (Ks) sensors but
vehicle manufacturers don't have a consistent way of using knock sensor
circuitry. There are generally two methods that manufacturers have for
using the knock sensor.
In the first design, which is found in most vehicles, the knock sensor
plays an active role in controlling ignition timing. In this system, the
PCM is advancing ignition timing until knock occurs and then retards
timing slightly. This system runs on the verge of engine knock at all
times. In this system the function of the knock sensor circuit is critical. If the sensor malfunctioned, precise ignition timing control could not be achieved.
A "dead" sensor circuit would not be able to detect actual knock, timing
would be overly advanced, and NOX exhaust emissions would increase. For
this reason, manufacturers that use the knock sensor in this manner are
required to monitor this sensor and light the MIL light when a
malfunction is detected.
In the second design, the knock sensor plays a very passive role and is
really only on the engine for protection purposes. The various engine
sensors send their information to the PCM to determine ignition timing.
The PCM uses this information to control the ignition timing based on
look-up tables stored in its memory. If ignition knock is detected, the
PCM will take action and ****** the timing a few degrees. This type of
control is generally used to control spark knock caused by changes in
Used in this way, the knock sensor is less critical to emissions and may
not even have a measurable emission impact. Unlike the first design, a
"dead" knock sensor in this system will have little to no effect on the
operation of the engine. Manufacturers that use this design are not
required to monitor the sensor under EPA OBDII regulations and will not
turn on the MIL if the P0325 DTC is set.
Remember, this sensor does not change the operation of the engine. The
customer will not notice any change in the way the vehicle operates. The
knock sensor system has a one trip detection logic and WILL NOT turn on the MIL or store Freeze Frame data.
How to Diagnose P0325
Most technicians know how this type of sensor operates. Its element
produces a voltage when the sensor picks up a vibration, usually caused
by engine detonation.Technicians then check the ohmic value of the sensor.
Maybe this was of some help.Your valuable feedback would be appreciated.Thanks for choosing Fixya.
Jun 09, 2011 |
2003 Jeep Liberty