Maintenance manual for sunray hfc4da1-2c china-IV diesel engines
127
2.
DTC
P0069
The boost pressure sensor drift
P0237
The boost pressure sensor output voltage is below the lower limit (the wiring
is short to ground).
P0238
The boost pressure sensor output voltage is above the upper limit (the wiring
is open or short to high level).
P0097
The voltage of intake air temperature sensor is too low (the wiring is short to
ground).
P0098
The voltage of intake air temperature sensor is too high (the wiring is open
or short to high level).
Fault Description: The boost pressure sensor shall make response to the pressure change of intake manifold. The
pressure changes with the engine load. The ECU shall supply 5V voltage to the 5V reference voltage circuit of boost
pressure sensor and also supply grounding for the low reference voltage circuit. The boost pressure sensor shall
provide a signal that is related to the pressure change of intake manifold to ECU via the boost pressure sensor signal
circuit. When the intake manifold pressure is relatively low (for example: during idling period), the low level signal
voltage shall be detected by the ECU. When it is relatively high (for example: with the accelerator pedal fully open
(WOT)), the high level signal voltage shall be detected. The boost pressure sensor is also for determining the
barometric pressure (BARO). When the ignition switch is turned on without starting the engine, the following
condition shall occur. As long as the accelerator pedal position sensor signal is more than 28%, the barometric
pressure reading shall be updated. The boost pressure sensor includes the following circuits:
z A 5V reference voltage circuit
z A low reference voltage circuit
z A MAP sensor signal circuit
If the boost pressure sensor signal detected by ECU is beyond the set range, relevant DTC shall be generated.
The intake air temperature (IAT) sensor is a kind of variable resistor that can measure the temperature of air into the
engine. The ECU shall supply 5V voltage to the signal circuit of IAT sensor and also supply grounding for the
reference voltage circuit of IAT sensor. When the IAT sensor is in cold state, the sensor resistance is relatively high.
When the air temperature increases, the sensor resistance shall decrease. When the sensor resistance is relatively high,
the voltage of IAT sensor signal circuit detected by ECU shall be relatively high. With the decrease of sensor
resistance, the voltage of IAT sensor signal circuit detected by ECU shall decrease also. If the signal voltage of IAT
sensor detected by ECU is too low (indicating the temperature is too high), or too high (indicating the temperature is
too low), relevant DTC shall be generated.
Boost pressure /
intake air
temperature sensor
5V power supply
Pressure signal
Ground
Temperature signal