Boost Pressure Sensor(BPS) is installed in intake manifold and senses the pressure of air inside of intake manifold which is compressed by turbo charager.
Measuring mass air flow accurately with the information of intake mainfold pressure, mass air flow and intake air temperature, ECM performs actuating correction of EGR and VGT.
When excessive intake manifold pressure is detected, engine power generation is limited to protect engine because too highly compressed pressure due to turbo charger may harm engine.
P0238 is set when BPS output voltage is higher than maximum value (4900mV) for more than 2 sec.. This code is due to 1) short to battery / open in signal circuit or 2) open in ground circuit.
Item
Detecting Condition
Possible Cause
DTC Strategy
Voltage monitoring
BPS circuit
BPS
Enable Conditions
IG key ON
Threshold Value
Output voltage is higher than maximum value (4900mV).
- Short to battery in signal circuit.
- Open in signal circuit
- Open in ground circuit.
Diagnostic Time
2 sec.
Fail Safe
Fuel cut
NO
-
EGR Off
YES
Fuel Limit
Check Lamp
ON
Pressure[Kpa]
32.5
70
140
210
270
284
Output voltage[V]
0.5
1.02~1.17
2.13~2.28
3.25~3.40
4.20~4.35
4.5
Fig.1) The waveform of BPS signal as accelerating from idle state. Signal voltage rises as accelerating.