DTC P0181: Fuel Tank Temperature Sensor Circuit Range/Performance

CIRCUIT OPERATION
• 5-volt voltage is applied to the fuel tank temperature sensor output terminal (terminal No. 3) from the ECM (terminal No. 77) <M/T> or PCM (terminal No. 51) <A/T> via the resistor in the ECM <M/T> or PCM <A/T>.
• 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 <M/T> or PCM<A/T> detects the fuel tank temperature in the fuel tank with this output voltage.
DESCRIPTIONS OF MONITOR METHODS
• If the fuel tank temperature is found to be higher than the engine coolant temperature by a prescribed value, through a comparison between the engine coolant temperature and the fuel tank temperature when the engine is started cold, a malfunction is determined to have occurred.
MONITOR EXECUTION
Once per driving cycle
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)
• Intake air temperature sensor
• Engine coolant temperature sensor
DTC SET CONDITIONS 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 (96.8°F) when the engine is started.
Engine coolant temperature 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 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 13 .
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, or connector damage.
• ECM failed. <M/T>
• PCM failed. <A/T>
NOTE: A diagnostic trouble code (DTC) could be output if the engine coolant is changed as indicated below. 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.
The engine and the radiator have been flushed repeatedly when the engine coolant temperature was high (or the fuel tank temperature was high).