Fuel Temperature Sensor, Checking

Observe all safety precautions: SAFETY PRECAUTIONS

View clean working conditions: CLEAN WORKING CONDITIONS

Prior to repair work, perform a preliminary check to verify the condition. Refer to PRELIMINARY CHECK .

Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.

For wiring diagrams, component locations, and connector views, Refer to the applicable wiring diagram.

Special tools and workshop equipment required

Multimeter
Wiring diagram

Test requirements

The engine control module fuses OK
Battery voltage at least 12.5 volts
All electrical consumers switched off
Vehicles with automatic transmission, shift selector lever in park or neutral
A/C switched off
Ground connections between engine/transmission/chassis OK

Test procedure

-- Disconnect the Fuel Temperature Sensor -G81- electrical harness connector.

Checking internal resistance

-- Using a multimeter, measure the resistance between the terminals of the Fuel Temperature Sensor -G81-.

Use the chart below to estimate the specified values:

Fuel temperature	Sensor resistance
20° C (68° F)	1950 to 2200 Ω

If the sensor value was not within the specified range:

-- Replace the Fuel Temperature Sensor -G81-.

Checking the voltage

-- Disconnect the Fuel Temperature Sensor -G81- connector.

-- Turn the ignition switch ON.

-- Using a multimeter, measure the voltage between the Fuel Temperature Sensor -G81- terminal 2 and ground.

Specified value: near 5.0 V

If the specification was obtained:

-- Using a multimeter, measure the voltage between the Fuel Temperature Sensor -G81- terminals 2 and 1.

Specified value: near 5.0 V

If the voltages above were Not obtained:

Checking the wiring

-- Remove the Engine Control Module (ECM) -J623-. Refer to the service information for removal and installation procedures.

Fuel Temperature Sensor -G81- electrical harness connector terminal	Motronic Engine Control Module (ECM) -J623- electrical harness connector T60 terminals or test box socket
1	53
2	42

-- Using a multimeter, measure the resistance of circuits between the Fuel Temperature Sensor -G81- and the Engine Control Module (ECM) -J623- electrical harness connectors. Refer to the applicable wiring diagram.

Specified value: 1.5 Ω Max.

If the specification was not obtained:

-- Check the wires for high resistance, a short circuit to each other, a short to battery voltage, and a short to ground.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- Repair as necessary.

If no malfunction is detected in the sensor or wiring:

-- Replace the Engine Control Module (ECM) -J623-. Refer to the service information for removal and installation procedures.

Final procedures

After repair work, the following work steps must be performed in the following sequence:

Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .