Nissan Sentra B18 (2020-2025) Service Manual / Engine / Work Procedure (After Replacing Electric Throttle Control Actuator) / Dtc/circuit Diagnosis / P0181 Ftt Sensor

Nissan Sentra B18 (2020-2025) Service Manual: P0181 Ftt Sensor

Dtc Description

DTC Description

DTC DETECTION LOGIC

DTC	CONSULT screen terms (Trouble diagnosis content)	DTC detection condition
P0181	FTT SENSOR (Fuel temperature sensor ″A″ circuit range/performance)	A	Diagnosis condition	—
			Signal (terminal)	Fuel tank temperature sensor signal
			Threshold	Rationally incorrect voltage from the sensor is sent to ECM, compared with the voltage signals from ECT sensor and intake air temperature sensor.
			Diagnosis delay time	—
		B	Diagnosis condition	Engine cold start
			Signal (terminal)	Fuel tank temperature sensor signal
			Threshold	The comparison result of signals transmitted to ECM from each temperature sensor (IAT sensor, ECT sensor, EOT sensor, and FTT sensor) shows that the voltage signal of the FTT sensor is higher/lower than that of other temperature sensors when the engine is started with its cold state.
			Diagnosis delay time	—

POSSIBLE CAUSE

Malfunction A

Harness or connectors (FTT sensor circuit is open or shorted)
Fuel temperature sensor

Malfunction B

Harness or connectors (High or low resistance in the FTT sensor circuit)

Fuel temperature sensor

FAIL-SAFE

Not applicable

Confirmation Procedure

Confirmation Procedure

INSPECTION START

Is it necessary to erase permanent DTC?
YES >>
GO TO 7.
NO >>
GO TO 2.
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 3.
PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A-1
1. Turn ignition switch ON and wait at least 10 seconds.
2. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >>
Proceed to DTC Diagnosis Procedure.
NO >>
GO TO 4.
CHECK ENGINE COOLANT TEMPERATURE

With CONSULT
1. Select “COOLANT TEMP/S” in “DATA MONITOR” mode of “ENGINE” using CONSULT.
2. Check “COOLANT TEMP/S” value.
With GST

Follow the procedure “With CONSULT” above.

“COOLANT TEMP/S” less than 60°C (140°F)?
YES-1 >>
To check malfunction symptom before repair: Refer to Intermittent Incident.
YES-2 >>
Confirmation after repair: INSPECTION END
NO >>
GO TO 5.
PERFORM DTC CONFIRMATION PROCEDURE FOR MALFUNCTION A-2

With CONSULT
1. Cool engine down until “COOLANT TEMP/S” is less than 60°C (140°F).
2. Wait at least 10 seconds.
3. Check 1st trip DTC.
With GST

Follow the procedure “With CONSULT” above.

Is 1st trip DTC detected?
YES >>
Proceed to DTC Diagnosis Procedure.
NO >>
GO TO 6.

PERFORM COMPONENT FUNCTION CHECK FOR MALFUNCTION B

Note:

Use the component function check to check the overall function of the FTT sensor circuit. During this check, a 1st trip DTC might not be confirmed.

Turn ignition switch OFF.
Disconnect fuel level sensor unit and fuel pump harness connector.
Remove “fuel level sensor unit, fuel filter and fuel pump assembly”. Refer to Removal and Installation.

Check resistance between fuel level sensor unit and fuel pump terminals by heating with hot water as shown in the figure.

Fuel level sensor unit and fuel pump		Condition		Resistance
Terminal		Condition		Resistance
5	6	Temperature [°C (°F)]	20 (68)	2.3 – 2.7 kΩ
5	6	Temperature [°C (°F)]	50 (122)	0.79 – 0.90 kΩ

Is the inspection result normal?

YES-1 >>

To check malfunction symptom before repair: Refer to Intermittent Incident.

YES-2 >>

Confirmation after repair: INSPECTION END

NO >>

Proceed to DTC Diagnosis 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.

TESTING CONDITION:
- Before performing the following procedure, do not add fuel.
- Before performing the following procedure, check that fuel level is between 1/4 and 4/4.
- Before performing the following procedure, confirm that battery voltage is 11 V or more at idle.
>>
GO TO 8.
PERFORM DTC CONFIRMATION PROCEDURE
1. Move the Nissan Sentra vehicle to a cool place.
  Note:
  Cool the vehicle in an environment of ambient air temperature between −10°C (14°F) and 35°C (95°F).
2. Turn ignition switch OFF and leave the Nissan Sentra vehicle for 12 hours.
  
  CAUTION:
  
  Never turn ignition switch ON during this procedure.
  
  Note:
  The Nissan Sentra vehicle must be cooled with the hood open.
3. Start engine and let it idle for 5 minutes or more.
  
  CAUTION:
  
  Never turn ignition switch OFF during idling.
4. Check 1st trip DTC.
Is 1st trip DTC detected?
YES >>
Refer 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

INSPECTION START

Confirm the detected malfunction (A or B). Refer to DTC Description. Refer to DTC Description.

Which malfunction is detected?
A>>
GO TO 2.
B>>
GO TO 5.

CHECK FUEL TANK TEMPERATURE (FTT) SENSOR POWER SUPPLY

Turn ignition switch OFF.
Disconnect fuel level sensor unit and fuel pump harness connector.
Turn ignition switch ON.

Check the voltage between fuel level sensor unit and fuel pump harness connector and ground.

+	−	Voltage (Approx.)
B48	5	Ground	5 V

−

Voltage

(Approx.)

Fuel level sensor unit and fuel pump

Connector

Terminal

B48

Ground

5 V

Is the inspection result normal?

YES >>

GO TO 4.

NO >>

GO TO 3.

CHECK FTT SENSOR POWER SUPPLY CIRCUIT

Turn ignition switch OFF.
Disconnect ECM harness connector.

Check the continuity between fuel level sensor unit and fuel pump harness connector and ECM harness connector.

Fuel level sensor unit and fuel pump		ECM		Continuity
Connector	Terminal	Connector	Terminal	Continuity
B48	5	E16	138	Existed

Also check harness for short to ground and to power.

Is the inspection result normal?

YES >>

Perform the trouble diagnosis for power supply circuit.

NO >>

Repair or replace malfunctioning part.

CHECK FTT SENSOR GROUND CIRCUIT

Turn ignition switch OFF.
Disconnect ECM harness connector.

Check the continuity between fuel level sensor unit and fuel pump harness connector and ECM harness connector.

Fuel level sensor unit and fuel pump		ECM		Continuity
Connector	Terminal	Connector	Terminal	Continuity
B48	6	E16	158	Existed

Also check harness for short to power.

Is the inspection result normal?

YES >>

GO TO 5.

NO >>

Repair or replace malfunctioning part.

CHECK FTT SENSOR

Refer to DTC Description.

Is the inspection result normal?
YES >>
INSPECTION END
NO >>
Replace fuel level sensor unit, fuel filter and fuel pump assembly (with fuel tank temperature sensor). Refer to Removal and Installation.

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