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.2) 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 sensor is higher than 60°C (140°F).
- Maximum vehicle speed is higher than 30 km/h (19 mph) after the starting sequence has been completed.
Judgement Criteria
- 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 - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
TROUBLESHOOTING HINTS (The most likely causes for this code to be set are:)
- Fuel tank temperature sensor failed.
- Harness damage in fuel tank temperature sensor circuit 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 drive cycle pattern in order to verify that a DTC will not be output.
DIAGNOSIS
Required Special Tools:
- MB991958: Scan Tool (MUT-III Sub Assembly)
- MB991824: V.C.I.
- MB991827: USB Cable
- MB991911: Main Harness B
STEP 1. Using scan tool MB991958, check data list item 4A: 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 4A, Fuel Tank Temperature Sensor.
- With the engine cool, the fuel tank temperature should be approximately the same as ambient air temperature.
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. Refer to How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions.
NO: Go to Step 2.
STEP 2. Check harness connector D-10 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. Refer to Harness Connector Inspection. Then go to Step 7.
STEP 3. Check the fuel tank temperature sensor.
1. Disconnect the fuel tank temperature sensor connector D-10.
2. Measure the resistance between terminal No.2 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 7.
STEP 4. Check the continuity at fuel tank temperature sensor harness side connector D-10.
1. Disconnect the connector D-10 and measure at the harness side.
2. Check for the continuity between terminal No. 2 and ground.
- Should be less than 2 ohms.
Q: Does continuity exist?
YES: Go to Step 5.
NO: Check harness connector D-14 at intermediate connector for damage and repair or replace as required. Refer to Harness Connector Inspection. If intermediate connector is in good condition, repair harness wire between fuel tank temperature sensor connector D-10 (terminal No.2) and ground because of harness damage. Then go to Step 7.
STEP 5. Check harness connector C-137 at ECM
Q: Is the harness connector in good condition?
YES: Go to Step 6.
NO: Repair or replace it. Refer to Harness Connector Inspection. Then go to Step 7.
STEP 6. Check for harness damage between fuel tank temperature sensor connector D-10 (terminal No.3) and ECM connector C-137
NOTE: Check harness after checking intermediate connector C-122, C-127 and D-14. If intermediate connector are damaged, repair or replace it. Refer to Harness Connector Inspection. Then go to Step 7.
Q: Is the harness wire in good condition?
YES: Replace the ECM or PCM. Then go to Step 7.
NO: Repair it. Then go to Step 7.
STEP 7. 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 - Procedure 6 - Other Monitor. OBD-II Drive Cycle Pattern Lists
2. Check the diagnostic trouble code (DTC).
Q: Is DTC P0181 set?
YES: Retry the troubleshooting.
NO: The inspection is complete.