Nissan Sentra B18 (2020-2025) Service Manual: P2123 App Sensor

Nissan Sentra B18 (2020-2025) Service Manual / Engine / Work Procedure (After Replacing Electric Throttle Control Actuator) / Dtc/circuit Diagnosis / P2123 App Sensor

Dtc Description

DTC Description

DTC DETECTION LOGIC

DTC	CONSULT screen terms (Trouble diagnosis content)	DTC detection condition
P2123	APP SEN 1/CIRC (Throttle/Pedal position sensor/switch “D” circuit high)	Diagnosis condition	Engine running at idle
		Signal (terminal)	Accelerator pedal position sensor 1 signal
		Threshold	An excessively high voltage is sent to ECM
		Diagnosis delay time	—

POSSIBLE CAUSE

Harness or connectors (APP sensor 1 circuit is open or shorted.)
Accelerator pedal position sensor (APP sensor 1)

FAIL-SAFE

Engine Control System

Engine operating condition in fail-safe mode
Device fix mode	This mode fixes the electric IVT motor and the EVT control solenoid valve in the reference position. The intake manifold runner control valve motor is turned OFF (intake manifold runner control valve opens).
Others	The ECM controls the electric throttle control actuator in regulating the throttle opening in order for the idle position to be within +10 degrees. The ECM regulates the opening speed of the throttle valve to be slower than the normal condition. Therefore, the acceleration will be poor.

Engine operating condition in fail-safe mode

Fail safe mode

Nissan Sentra Vehicle behavior

Device fix mode

This mode fixes the electric IVT motor and the EVT control solenoid valve in the reference position.
The intake manifold runner control valve motor is turned OFF (intake manifold runner control valve opens).

Others

The ECM controls the electric throttle control actuator in regulating the throttle opening in order for the idle position to be within +10 degrees.

The ECM regulates the opening speed of the throttle valve to be slower than the normal condition. Therefore, the acceleration will be poor.

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

CHECK DTC PRIORITY

If DTC P2122 or P2123 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643.

Is applicable DTC detected?
YES >>
Perform diagnosis of applicable. Refer to DTC Description.
NO >>
GO TO 2.
PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.
1. Turn ignition switch OFF and wait at least 10 seconds.
2. Turn ignition switch ON.
3. 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 3.
PERFORM DTC CONFIRMATION PROCEDURE
1. Start the engine and let it idle for 1 second.
2. 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

CHECK DTC PRIORITY

If DTC P2122 or P2123 is displayed with DTC P0643, first perform the trouble diagnosis for DTC P0643.

Is applicable DTC detected?
YES >>
Perform diagnosis of applicable. Refer to DTC Description.
NO >>
GO TO 2.

CHECK APP SENSOR 1 POWER SUPPLY-1

Turn ignition switch OFF.
Disconnect accelerator pedal position (APP) sensor harness connector.
Turn ignition switch ON.

Check the voltage between APP sensor harness connector and ground.

APP sensor	Voltage (Approx.)
E12	4	2	5 V

APP sensor

Voltage

(Approx.)

Connector

−

Terminal

E12

5 V

Is the inspection result normal?

YES >>

GO TO 7.

NO >>

GO TO 3.

CHECK APP SENSOR 1 POWER SUPPLY-2

Check the voltage between APP sensor harness connector and ground.

+	−	Voltage (Approx.)
E12	4	Ground	5 V

−

Voltage

(Approx.)

APP sensor

Connector

Terminal

E12

Ground

5 V

Is the inspection result normal?

YES >>

GO TO 5.

NO >>

GO TO 4.

CHECK APP SENSOR 1 POWER SUPPLY CIRCUIT

Turn ignition switch OFF.
Disconnect ECM harness connector.

Check the continuity between APP sensor harness connector and ECM harness connector.

APP sensor		ECM		Continuity
Connector	Terminal	Connector	Terminal	Continuity
E12	4	E16	156	Existed

Also check harness for short to ground and to power.

Is the inspection result normal?

YES >>

Perform the trouble diagnosis for ECM power supply circuit. Refer to Diagnosis Procedure.

NO >>

Repair or replace malfunctioning part.

CHECK APP SENSOR 1 GROUND CIRCUIT

Turn ignition switch OFF.
Disconnect ECM harness connector.

Check the continuity between APP sensor harness connector and ECM harness connector.

APP sensor		ECM		Continuity
Connector	Terminal	Connector	Terminal	Continuity
E12	2	E16	161	Existed

Also check harness for short to ground and to power.

Is the inspection result normal?

YES >>

GO TO 6.

NO >>

Repair or replace malfunctioning part.

CHECK ECM GROUND CIRCUIT

Check the continuity between ECM harness connector and ground.

ECM		—	Continuity
Connector	Terminal	—	Continuity
F24	5	Ground	Existed
F24	65
F25	69
E16	157
	159
	162

Also check harness for short to power.

Is the inspection result normal?

YES >>

INSPECTION END

NO >>

Repair or replace malfunctioning part.

CHECK APP SENSOR 1 INPUT SIGNAL CIRCUIT

Turn ignition switch OFF
Disconnect ECM harness connector.

Check the continuity between APP sensor harness connector and ECM harness connector.

APP sensor		ECM		Continuity
Connector	Terminal	Connector	Terminal	Continuity
E12	3	E16	160	Existed

Also check harness for short to ground and to power.

Is the inspection result normal?

YES >>

GO TO 8.

NO >>

Repair or replace malfunctioning part.

CHECK APP SENSOR

Check the APP sensor. Refer to Component Inspection.

Is the inspection result normal?
YES >>
INSPECTION END
NO >>
Replace accelerator pedal assembly. Refer to Removal and Installation.

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