Engine Coolant Temperature Sensor On Radiator, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Motronic Engine Control Module (ECM) - J220- fuses OK.
  Fig 1: Fuses On E-Box In Engine Compartment, Left Side

  Courtesy of AUDI OF AMERICA, LLC
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, shift selector lever into position "P" or "N".
• A/C switched off.
• Ground (GND) connections between engine/transmission/chassis OK.
• Ignition switched off.
• Engine cold.

Test procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK .

Start diagnosis 

Checking internal resistance 

-- Disconnect the Engine Coolant Temperature (ECT) Sensor (on Radiator) -G83- electrical harness connector -1-.

-- Using a multimeter, check the Engine Coolant Temperature (ECT) Sensor (on Radiator) -G83- terminals 1 to 2 for resistance.

Use the chart below for the specified values:

Specified values:

ECT Temperature vs Resistance
Temp (C)	min value ohms	max value ohms
- 40	36816	43714
- 35	28840	33978
- 25	17680	20530
- 15	10940	12534
- 5	6897	7804
0	5535	6226
5	4443	4970
15	2923	3235
25	1978	2167
35	1369	1486
45	965	1039
55	692	738
65	503	533
75	372	392
85	279	292
95	213	223
105	164	172
115	127	134
125	99	106
135	78	84

If any of the specified values was not obtained:

-- Replace the Engine Coolant Temperature (ECT) Sensor (on Radiator) -G83-. Refer to the appropriate service information.

If any of the specified values was obtained:

Checking wiring 

If the manufacturers test box is being used. Perform the following step.

-- Install the test box. Refer to the appropriate service information.

If the manufacturers test box is not being used. Perform the following step.

-- Remove the Motronic Engine Control Module (ECM) -J220-. Refer to the appropriate service information.

-- Using a Multimeter --, check the Engine Coolant Temperature (ECT) Sensor (on Radiator) -G83- electrical harness connector terminals to the Motronic Engine Control Module (ECM) -J220- electrical harness connector T121 terminals for an open circuit according to the wiring diagram.

Engine Coolant Temperature (ECT) Sensor (on Radiator) -G83- electrical harness connector terminals	Motronic Engine Control Module (ECM) -J220- electrical connector 121 terminals or test box socket
1	17
2	50

Specified value: 1.5 Ω Max.

If the specification was not obtained:

-- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

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

-- If necessary, repair the faulty wiring connection.

If no malfunction is detected in the wiring:

-- Replace the Motronic Engine Control Module (ECM) -J220-. Refer to the appropriate service information.

Final procedures 

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

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