P0181
DTC P0181: Fuel Tank Temperature Sensor Circuit Range/PerformanceFuel Tank Temperature Sensor Circuit Part 1:
Fuel Tank Temperature Sensor Circuit Part 2:
CIRCUIT OPERATION
- 5-volt voltage is applied to the fuel tank temperature sensor output terminal (terminal No. 3) from the ECM
- The fuel tank temperature sensor output voltage increases when the resistance increases and decreases when the resistance decreases. The ground terminal (terminal No. 1) is grounded to the vehicle body.
TECHNICAL DESCRIPTION
- The fuel tank temperature sensor converts the fuel tank temperature to a voltage.
- The ECM
DESCRIPTIONS OF MONITOR METHODS
Fuel tank temperature at engine start is higher than engine coolant temperature at engine start by specified value when engine is cold start condition.
MONITOR EXECUTION
Continuous
MONITOR EXECUTION CONDITIONS (Other monitor and Sensor)
Other Monitor (There is no temporary DTC stored in memory for the item monitored below)
- Not applicable
Sensor (The sensor below is determined to be normal)
- Engine coolant temperature sensor
- Intake air temperature sensor
DTC SET CONDITIONS
Logic Flow Chart:
Logic Flow Chart
Check Conditions
- The engine coolant temperature - intake air temperature is 5 °C (9 °F) or less when the engine is started.
- The engine coolant temperature is between -10 °C (14 °F) and 36 °C (97 °F) when the engine is started.
- The engine coolant temperature is higher than 60 °C (140 °F).
- Maximum vehicle speed is higher than 30 km/h (19 mph) after the engine starting sequence has been completed.
Judgement Criterion
- The fuel tank temperature - engine coolant temperature is 15 °C (27 °F) or more when the engine is started.
OBD-II DRIVE CYCLE PATTERN
Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 14. OBD-II Drive Cycle
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are)
- Fuel tank temperature sensor failed.
- Open or shorted fuel tank temperature sensor circuit, harness damage, or connector damage.
- ECM failed.
- PCM failed.
NOTE: A diagnostic trouble code (DTC) could be output if the engine and the radiator have been flushed repeatedly when the engine coolant temperature was high (or the fuel tank temperature was high). Because this is not a failure, the DTC must be erased.
Make sure to test drive the vehicle in accordance with the OBD-II drive cycle pattern in order to verify that a DTC will not be output.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (M.U.T.-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991910: Main Harness A
- MB991923: Power Plant ECU Check Harness
STEP 1. Using scan tool MB991958, check data list item 53: Fuel Tank Temperature Sensor.
CAUTION: To prevent damage to scan tool MB991958, always turn the ignition switch to the "LOCK" (OFF) position before connecting or disconnecting scan tool MB991958.
1. Connect scan tool MB991958 to the data link connector.
2. Turn the ignition switch to the "ON" position.
3. Set scan tool MB991958 to the data reading mode for item 53, Fuel Tank Temperature Sensor.
- Approximately the same as the ambient air temperature when the engine is cooled.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the sensor operating properly?
YES: It can be assumed that this malfunction is intermittent.
NO: Go to Step 2.
STEP 2. Check harness connector D-19 at the fuel tank temperature sensor for damage.
Q: Is the harness connector in good condition?
YES: Go to Step 3.
NO: Repair or replace it. Then go to Step 12.
STEP 3. Check the fuel tank temperature sensor.
1. Disconnect the fuel tank temperature sensor connector D-19.
2. Measure the resistance between terminal No. 1 and No. 3 of the fuel tank temperature sensor.
Standard value: 0.5 - 12.0 kohms
Q: Is the measured resistance between 0.5 and 12.0 kohms?
YES: Go to Step 4.
NO: Replace the fuel tank temperature sensor. Then go to Step 12.
STEP 4. Check the continuity at fuel tank temperature sensor harness side connector D-19.
1. Disconnect the connector D-19 and measure at the harness side.
2. Check for the continuity between terminal No. 1 and ground.
- Should be less than 2 Ohms.
Q: Does continuity exist?
YES: Go to Step 5.
NO: Repair harness wire between fuel tank temperature sensor connector D-19 (terminal No. 1) and ground because of open circuit or harness damage. Then go to Step 12.
STEP 5. Measure the sensor supply voltage at fuel tank temperature sensor harness side connector D-19.
1. Disconnect the connector D-19 and measure at the harness side.
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 3 and ground.
- Voltage should be between 4.5 and 4.9 volts
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage between 4.5 and 4.9 volts?
YES: Go to Step 6.
NO: Go to Step 10.
STEP 6. Measure the sensor supply voltage at ECM
1. Disconnect all ECM
2. Turn the ignition switch to the "ON" position.
3. Measure the voltage between terminal No. 41 and ground.
- When fuel tank temperature is 0 °C (32 °F), voltage should be between 2.7 and 3.1 volts.
- When fuel tank temperature is 20 °C (68 °F), voltage should be between 2.1 and 2.5 volts.
- When fuel tank temperature is 40 °C (104 °F), voltage should be between 1.6 and 2.0 volts.
- When fuel tank temperature is 80 °C (176 °F), voltage should be between 0.8 and 1.2 volts.
4. Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage normal?
YES: Go to Step 7.
NO: Go to Step 8.
STEP 7. Check harness connector B-19 at ECM
Q: Is the harness connector in good condition?
YES: Check harness connector C-26 at intermediate connector for damage, and repair or replace as required. If intermediate connector is in good condition, repair harness wire between fuel tank temperature sensor connector D-19 (terminal No. 3) and ECM
NO: Repair or replace it. Then go to Step 12.
STEP 8. Check harness connector B-19 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 9.
NO: Repair or replace it. Then go to Step 12.
STEP 9. Check for short circuit to ground between fuel tank temperature sensor connector D-19 (terminal No. 3) and ECM
NOTE: Check harness after checking intermediate connector C-26. If intermediate connector is damaged, repair or replace it. Then go to Step 12.
Q: Is the harness wire in good condition?
YES: Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Refer to Encrypted Code Registration Criteria Table. Then go to Step 12.
NO: Repair it. Then go to Step 12.
STEP 10. Check harness connector B-19 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 11.
NO: Repair or replace it. Then go to Step 12.
STEP 11. Check for harness damage between fuel tank temperature sensor connector D-19 (terminal No. 3) and ECM
NOTE: Check harness after checking intermediate connector C-26. If intermediate connector is damaged, repair or replace it. Then go to Step 12.
Q: Is the harness wire in good condition?
YES: Replace the ECM or the PCM. When the ECM or the PCM is replaced, register the encrypted code. Refer to Encrypted Code Registration Criteria Table. Then go to Step 12.
NO: Repair it. Then go to Step 12.
STEP 12. Test the OBD-II drive cycle.
1. Carry out a test drive with the drive cycle pattern. Refer to Diagnostic Function - OBD-II Drive Cycle - Pattern 14. OBD-II Drive Cycle
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0181 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.