Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provide an overview of each diagnostic category. |
DTC Descriptor
DTC P0181: Fuel Temperature Sensor PerformanceCircuit/System Description
The fuel temperature sensor is a thermistor. The engine control module (ECM) supplies the fuel temperature sensor a bias voltage of 5 volts on the signal circuit and also provides a low reference circuit to the sensor. When the fuel temperature sensor is cold, the resistance is high. The fuel temperature sensor signal voltage remains near the bias voltage cold and decreases as the sensor warms. The ECM monitors the fuel temperature sensor signal circuit in order to calculate the temperature of the fuel entering the engine.
Conditions for Running the DTC
| • | DTC P0016, P0116, P0117, P0118, P0126, P0182, P0183, P0201, P0202, P0203, P0204, P0205, P0206, P0234, P0261, P0264, P0267, P0270, P0273, P0276, P0299, P0335, P0336, P0500, P0602, P0642, P0643, P0652, P0653, P1293, P2146, P2147, P2148, P2149, P2150, P2151 and P268A are not set. |
| • | Battery voltage is between 10-16 V. |
| • | Key switch is ON for longer than 2 seconds. |
| • | Elapsed time from starter switch OFF for longer than 2 seconds. |
| • | No engine start-up mode. |
| • | Engine is running. |
| • | Diagnosis permission duration time for fuel temperature sensor is between 102-840 seconds. |
| • | Accumulation time of vehicle running is more than 480 seconds with the vehicle speed more than 25 km/h (16 mph). |
| • | Accumulation injection quantity for fuel temperature sensor diagnosis is more than 390,000 mm³. |
| • | Start-up ECT is between -7° to +60°C (+19 to +140°F). |
| • | Current ECT is less than 60° (140°F). |
| • | Start-up fuel temperature is between -40 to +214°C (-40 to +417°F). |
Conditions for Setting the DTC
Difference of maximum fuel temperature and minimum fuel temperature is less than 1°C (1.8°F).
Action Taken When the DTC Sets
| • | The ECM illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. |
| • | The ECM records the operating conditions at the time the diagnostic fails. The ECM writes the operating conditions to the Freeze Frame and updates the Failure Records. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
| • | A short to a separate 5-volt source may set this DTC. |
| • | A skewed sensor could result in driveability concerns. |
Reference Information
Schematic Reference
Connector End View Reference
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
Important: If you cannot duplicate the condition, operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Turn ON the ignition and observe the Fuel Temperature Sensor parameter with a scan tool. The fuel temperature parameter should be within -30 to +120°C (-22 to +248°F).
Circuit/System Testing
- Disconnect the fuel temperature sensor .
- Turn ON the ignition, with the engine OFF.
- Observe the Fuel Temperature parameter with a scan tool.
- Connect a 3A fused jumper wire between the fuel temperature sensor signal circuit and the low reference circuit.
- If all circuits test normal, refer to Component Testing in this diagnostic.
| ⇒ | If the fuel temperature is warmer than -40°C (-40°F), test the signal circuit for a short to ground. |
| ⇒ | If the fuel temperature is colder than 135°C (275°F), test for high resistance in the signal circuit or the low reference circuit. |
Component Testing
- Disconnect the fuel temperature sensor and measure the resistance of the sensor with a DMM.
- Record the values at varies engine temperatures and compare those results to the Temperature vs. Resistance Table (Fuel Temperature).
| ⇒ | If the sensor does not closely match through the temperature ranges, replace the fuel temperature sensor. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
