Nissan Sentra B18 (2020-2025) Service Manual: P0078 Evt Control Solenoid Valve

Nissan Sentra B18 (2020-2025) Service Manual / Engine / Work Procedure (After Replacing Electric Throttle Control Actuator) / Dtc/circuit Diagnosis / P0078 Evt Control Solenoid Valve

Dtc Description

DTC Description

DTC DETECTION LOGIC

DTC	CONSULT screen terms (Trouble diagnosis content)	DTC detection condition
P0078	EX V/T ACT/CIRC-B1 (Exhaust valve control solenoid circuit bank 1)	Diagnosis condition	Engine running at idle
		Signal (terminal)	Exhaust valve timing control solenoid valve signal
		Threshold	An improper voltage is sent to the ECM through exhaust valve timing control solenoid valve
		Diagnosis delay time	—

POSSIBLE CAUSE

Harness or connectors (Exhaust valve timing control solenoid valve circuit is open or shorted.)
Exhaust valve timing control solenoid valve

FAIL-SAFE

Engine Control System

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).

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 turn ignition switch OFF and wait at least 10 seconds before conducting the next test.

>>
GO TO 2.
PERFORM DTC CONFIRMATION PROCEDURE
1. Start the engine and let it idle for at least 5 seconds.
2. Check 1st trip DTC.
Is 1st trip 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 P0078 is displayed with DTC P0090 and P1197, first perform the trouble diagnosis for DTC P0090 and P1197.

Is applicable DTC detected?
YES >>
Perform diagnosis of applicable.
- DTC P0090: Refer to DTC Description.
- DTC P1197: Refer to DTC Description.
NO >>
GO TO 2.
BLEED THE FUEL LINE
1. Start the engine, and let the engine run at idle at least for 10 minutes.
2. Perform DTC confirmation procedure of DTC P0078.
Is 1st trip DTC detected?
YES >>
GO TO 3.
NO >>
GO TO 7.
CHECK LOW FUEL PRESSURE

Check low fuel pressure. Refer to Work Procedure.

Is inspection result normal?
YES >>
GO TO 4.
NO >>
Check low fuel pressure system. Refer to Diagnosis Procedure.

CHECK LOW PRESSURE FUEL LINE FOR INTERNAL LEAKAGE

Turn ignition switch OFF.
Turn ignition switch ON.

Check the following value 30 minutes after turning the ignition switch ON.

Low fuel pressure

: 206 kPa (2.1 bar, 2.2 kgf/cm2, 30 psi) or more

Is inspection result normal?

YES >>

GO TO 5.

NO >>

Replace “fuel level sensor unit and fuel pump”. Refer to Removal and Installation.

CHECK HIGH PRESSURE FUEL PUMP

Check high pressure fuel pump. Refer to Component Inspection.

Is inspection result normal?
YES >>
GO TO 6.
NO >>
Repair or replace the error-detected parts.
CHECK HIGH PRESSURE FUEL PUMP LIFTER

Check high pressure fuel pump lifter. Refer to Removal and Installation.

Does the lifter top surface have scratches and/or dents?
YES >>
Replace the error-detected parts.
NO >>
INSPECTION END

CHECK LOW PRESSURE FUEL LINE FOR INTERNAL LEAKAGE

Turn ignition switch OFF.
Connect fuel pressure gauge. Refer to Work Procedure.
Turn ignition switch ON.

Check the following value 30 minutes after turning the ignition switch ON.

Low fuel pressure

: 206 kPa (2.1 bar, 2.2 kgf/cm2, 30 psi) or more

Is inspection result normal?

YES >>

INSPECTION END

NO >>

Replace “fuel level sensor unit and fuel pump”. Refer to Removal and Installation.

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