P0181

Advanced Diagnostics - DTC P0181: Fuel Temperature Sensor Circuit Range/Performance Problem






General Description
The fuel temperature sensor is located on the fuel rail and detects the temperature of the fuel. This signal is used to adjust the fuel injector duration according to the fuel temperature. When the engine stops and enough time has passed, each part of the vehicle becomes the same temperature as the ambient temperature. At step 1, the two coolant temperature sensors are compared to judge if the intake temperature sensor reading is normal. When the intake air temperature (IAT) sensor is judged as normal, the intake temperature sensor and CNG fuel temperature sensor are compared at step 2, and if an improper temperature is detected, a CNG fuel temperature sensor problem is detected and a DTC is stored.

Monitor Execution, Sequence, Duration, DTC Type, OBD Status






Enable Conditions






Malfunction Threshold
When the temperature difference between the fuel temperature sensor and IAT is 45 °F (25 °C) or more.

Driving Pattern
1. Turn the ignition switch to LOCK (0), and wait at least 6 hours.
2. Start the engine, and let it idle for at least 10 seconds.

Diagnosis Details

Conditions for setting the DTC
When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC
The MIL is cleared if the malfunction does not return in three consecutive drive cycles in which the engine conditions are similar to the first time the malfunction was detected. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the battery.