Nissan Sentra B18 (2020-2025) Service Manual: P0643 Sensor Power Supply
Dtc Description
DTC Description
ECM supplies a voltage of 5 V to some of the sensors systematically divided into 2 groups, respectively.
Accordingly, when a short circuit develops in a sensor power source, a malfunction may occur simultaneously in the sensors belonging to the same group as the short-circuited sensor.
Sensor power supply 1
-
APP sensor 1
-
Crankshaft position sensor
-
EGR volume control valve position sensor
-
Exhaust camshaft position sensor
-
Intake manifold runner control valve position sensor
-
Manifold absolute pressure sensor
-
Throttle position sensor
If sensor power supply 1 circuit is malfunctioning, DTC P0643 is displayed.
Sensor power supply 2
-
APP sensor 2
-
Intake camshaft position sensor
-
Engine oil pressure sensor
-
Fuel rail pressure sensor
-
Mass air flow sensor
-
Refrigerant pressure sensor
DTC DETECTION LOGIC
|
DTC |
CONSULT screen terms (Trouble diagnosis content) |
DTC detection condition |
|
|
P0643 |
SENSOR POWER/CIRC (Sensor reference voltage “A” circuit high) |
Diagnosis condition |
Engine running at idle |
|
Signal (terminal) |
Sensor power supply 1 signal |
||
|
Threshold |
ECM detects that the voltage of sensor power supply 1 is excessively low or high |
||
|
Diagnosis delay time |
— |
||
POSSIBLE CAUSE
-
Harness or connectors
-
APP sensor 1 circuit is shorted.
-
Crankshaft position sensor circuit is shorted.
-
EGR volume control valve position sensor circuit is shorted.
-
Exhaust camshaft position sensor circuit is shorted.
-
Intake manifold runner control valve position sensor circuit is shorted.
-
Manifold absolute pressure sensor circuit is shorted.
-
TP sensor circuit is shorted.
-
-
Accelerator pedal position sensor
-
Crankshaft position sensor
-
EGR volume control valve position sensor
-
Exhaust camshaft position sensor
-
Intake manifold runner control valve position sensor
-
Manifold absolute pressure sensor
-
Throttle position sensor
FAIL-SAFE
Engine Control System
|
Engine operating condition in fail-safe mode |
||
|---|---|---|
|
Fail safe mode |
Nissan Sentra Vehicle behavior |
|
|
Device fix mode |
|
|
|
Others |
ECM stops the electric throttle control actuator control, throttle valve is maintained at a fixed opening (approx. 5 degrees) by the return spring. |
|
Idle Start/Stop System
When a DTC is detected, the start/stop indicator lamp blinks slowly and the idle start/stop system operation is prohibited.
When ECM detects error while operating the idle start/stop system, ECM restarts the engine.
Confirmation Procedure
Confirmation Procedure
-
PRECONDITIONING
If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
-
Turn ignition switch OFF and wait at least 10 seconds.
-
Turn ignition switch ON.
-
Turn ignition switch OFF and wait at least 10 seconds.
TESTING CONDITION:
Before performing the following procedure, confirm that battery voltage is more than 8 V at idle.
>>GO TO 2.
-
-
PERFORM DTC CONFIRMATION PROCEDURE
-
Start engine and let it idle for 1 second.
-
Check DTC.
Is DTC detected?
YES >>Proceed to DTC Diagnosis Procedure.
NO-1 >>To check malfunction symptom before repair: Refer to Intermittent Incident.
NO-2 >>Confirmation after repair: INSPECTION END
-
Dtc Diagnosis Procedure
DTC Diagnosis Procedure
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CHECK ACCELERATOR PEDAL POSITION SENSOR 1 POWER SUPPLY CIRCUIT
-
Disconnect accelerator pedal position (APP) sensor harness connector.
-
Turn ignition switch ON.
-
Check the voltage between APP sensor harness connector and ground.
+
−
Voltage
(Approx.)
APP sensor
Connector
Terminal
E12
4
Ground
5 V
Is the inspection result normal?
YES >>Proceed to Component Inspection.
NO >>GO TO 2.
-
-
CHECK SENSOR POWER SUPPLY CIRCUITS
Check harness for short to power and short to ground, between the following terminals.
ECM
Sensor
Connector
Terminal
Name
Connector
Terminal
F24
21
Crankshaft position sensor
F22*1
F40*2
3
28
Exhaust camshaft position sensor
F57
1
54
Manifold absolute pressure sensor
F76
1
F25
83
EGR volume control valve position sensor
F94
3
Intake manifold runner control valve position sensor
F29
1
95
Throttle position sensor
F7
3
E16
156
APP sensor 1
E12
4
*1: Without idle start/stop system
*2: With idle start/stop system
Is the inspection result normal?
YES >>GO TO 3.
NO >>Repair or replace malfunctioning part.
-
CHECK COMPONENTS
Check the following.
-
Crankshaft position sensor Refer to Component Inspection.
-
EGR volume control valve Refer to Component Inspection.
-
Exhaust camshaft position sensor Refer to Component Inspection.
-
Intake manifold runner control valve position sensor Refer to Component Inspection.
-
Manifold absolute pressure sensor Refer to Component Inspection.
-
Throttle position sensor Refer to Component Inspection.
Is the inspection result normal?
YES >>INSPECTION END
NO >>Repair or replace malfunctioning part.
-
Other materials:
P0014 Evt Control
Dtc Description
DTC Description
DTC DETECTION LOGIC
DTC
CONSULT screen terms
(Trouble diagnosis
content)
DTC detection
condition
...
B1040-22 Vehicle Speed
Dtc Description
DTC Description
DTC DETECTION LOGIC
Note:
This DTC may be detected when drive the Nissan Sentra vehicle
at vehicle speed of 186 MPH (300 km/h) or more.
DTC No.
CONSULT sc ...
Maintenance precautions
When performing any inspection, servicing, or maintenance work on your Nissan
Sentra, always exercise extreme care to avoid serious personal injury or accidental
damage to the vehicle. Routine maintenance plays an important role in the long-term
reliability, safety, and performance of the Niss ...