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Volkswagen New Beetle. Manual - part 1863

Start engine and idle. Using scan tool, observe ECT sensor temperature value. Temperature value should
steadily increase. If ECT sensor temperature value did not steadily increase, replace faulty ECT sensor.
Erase DTC memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE .

4. If ECT sensor temperature value is extremely high, approximately 285°F (141°C), possible cause is short

to ground. Go to step 6 . If ECT sensor temperature value is extremely low, approximately -50°F (-46°C),
possible cause is open circuit or short to positive. Go to next step.

5. Disconnect ECT sensor harness connector. See Fig. 29 . Using a jumper wire, bridge terminal with

Brown/Blue wire and terminal No. 3 of ECT sensor harness connector. See Fig. 32 . Using scan tool,
observe ECT sensor temperature value. If ECT sensor temperature value is approximately -50°F (46°C),
turn ignition off. Go to step 7 . If ECT sensor temperature value is approximately 285°F (141°C), turn
ignition off. Replace faulty ECT sensor. Erase DTC memory. Verify repair. Test is complete. Perform
ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .

6. Disconnect ECT sensor harness connector. See Fig. 29 . Using scan tool, observe ECT sensor

temperature value. If after disconnecting ECT sensor harness connector, temperature value is
approximately 285°F (141°C), turn ignition off. Go to next step. If after disconnecting ECT sensor
harness connector, temperature value is approximately -50°F (-46°C), turn ignition off. Replace faulty
ECT sensor. Erase DTC memory. Verify repair. Test is complete. Perform ECM relearn procedure. See
TEST DRIVE RELEARN PROCEDURE .

7. Disconnect ECM harness connector, leave ECM disconnected from test box. Connect Test Box (VAG

1598/31) to ECM harness connector. See CONNECTING VAG TEST BOX . Disconnect ECT sensor
4-pin connector. See Fig. 29 . Using DVOM, measure resistance between ECT sensor harness connector
terminal No. 3 and test box socket No. 93. See Fig. 32 . Record resistance reading. Measure resistance
between ECT sensor harness connector terminal No. 4 and test box socket No. 108. Record resistance
reading. Resistance should be a maximum of 1.5 ohms for each reading. Go to next step.

8. Check ECT sensor harness connector terminal No. 3 for short circuit to test box socket No. 108. Check

ECT sensor harness connector terminal No. 3 for short circuit to battery positive and ground. Check ECT
sensor harness connector terminal No. 4 for short circuit to battery positive. Repair as necessary. Erase
DTC memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE . If wiring and ECT sensor are okay, replace faulty ECM. See ENGINE
CONTROL MODULE REMOVAL & INSTALLATION . Erase DTC memory. Verify repair. Test is
complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .

Test Procedure - Passat

to 1.5 degree increments. If engine does not run smoothly in certain
temperature ranges and temperature value does not increase without
interruption, signal is intermittent. ECT sensor must be replaced. After
repairs, erase DTC memory.

WARNING:

To avoid injury, allow cooling system to cool and carefully release system
pressure.

NOTE:

Engine must be cold before performing test procedure.

2003 Volkswagen New Beetle GLS

2002-2003 ENGINE PERFORMANCE Self-Diagnostics - 1.8L Turbo

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1. Disconnect ECT sensor harness connector. See Fig. 31 . Using DVOM, measure resistance of ECT sensor

between ECT sensor terminals C and D. See Fig. 30 . See ECT SENSOR (G62) RESISTANCE table. If
ECT sensor resistance is okay, reconnect ECT sensor harness connector. Go to next step. If resistance is
not okay, replace faulty ECT sensor. After repairs, erase DTC memory. Go to next step.

2. Verify battery voltage is a minimum of 11.5 volts and all fuses are okay. Repair as necessary. Connect

Scan Tool. See RETRIEVING DIAGNOSTIC TROUBLE CODES . Turn ignition on. Using scan
tool, check ECT sensor temperature value. If ECT sensor temperature value deviates greatly from ECT
sensor ambient temperature, go to step 4 . If ECT sensor temperature value is approximately the same as
ECT sensor ambient temperature, go to next step.

4. If ECT sensor temperature value is extremely high, approximately 285°F (141°C), possible cause is short

to ground. Go to step 6 . If ECT sensor temperature value is extremely low, approximately -50°F (-46°C),
possible cause is open circuit or short to positive. Go to next step.

5. Disconnect ECT sensor harness connector. See Fig. 31 . Using a jumper wire, bridge terminals No. 3 and

4 of ECT sensor harness connector. See Fig. 32 . Using scan tool, observe ECT sensor temperature value.
If ECT sensor temperature value is approximately -50°F (46°C), turn ignition off. Go to step 7 . If ECT
sensor temperature value is approximately 285°F (141°C), turn ignition off. Replace faulty ECT sensor.
Erase DTC memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE .

6. Disconnect ECT sensor harness connector. See Fig. 31 . Using scan tool, observe ECT sensor

7. Disconnect ECM harness connector, leave ECM disconnected from test box. Connect Test Box (VAG

1598/31) to ECM harness connector. See CONNECTING VAG TEST BOX . Disconnect ECT sensor
4-pin harness connector. See Fig. 31 . Using DVOM, measure resistance between ECT sensor harness
connector terminal No. 3 and test box socket No. 108. See Fig. 32 . Record resistance reading. Measure

NOTE:

To bleed cooling system, fill cooling system. Warm engine to operating
temperature, (run engine until coolant fan starts), do not allow engine to
overheat, let engine cool and recheck coolant level.

NOTE:

Next test step tests ECT sensor through its full range.

NOTE:

Scan Tool (VAG 1551) and (VAG 1552) displays temperature in 1 to 1.5
degree increments. If engine does not run smoothly in certain temperature
ranges and temperature value does not increase without interruption,
signal is intermittent. ECT sensor must be replaced. After repairs, erase
DTC memory.

2003 Volkswagen New Beetle GLS

2002-2003 ENGINE PERFORMANCE Self-Diagnostics - 1.8L Turbo

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resistance between ECT sensor harness connector terminal No. 4 and test box socket No. 93. Record
resistance reading. Resistance should be a maximum of 1.5 ohms for each reading. Go to next step.

8. Check ECT sensor harness connector terminal No. 3 for short circuit to test box socket No. 93. Check

ECT sensor harness connector terminal No. 4 for short circuit to battery positive and ground. Check ECT
sensor harness connector terminal No. 3 for short circuit to battery positive. Repair as necessary. Erase
DTC memory. Verify repair. Test is complete. Perform ECM relearn procedure. See TEST DRIVE
RELEARN PROCEDURE . If wiring and ECT sensor are okay, replace faulty ECM. See ENGINE
CONTROL MODULE REMOVAL & INSTALLATION . Erase DTC memory. Verify repair. Test is
complete. Perform ECM relearn procedure. See TEST DRIVE RELEARN PROCEDURE .

ECT SENSOR (G62) RESISTANCE

Temperature °F (°C)

Ohms

86 (30)

1500-2000

104 (40)

1000-1500

122 (50)

800-1000

140 (60)

500-700

158 (70)

375-500

176 (80)

275-375

194 (90)

225-275

2003 Volkswagen New Beetle GLS

2002-2003 ENGINE PERFORMANCE Self-Diagnostics - 1.8L Turbo

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Fig. 26: Locating ECT Sensor (G62 - Beetle - Engine Code AWV)
Courtesy of VOLKSWAGEN UNITED STATES, INC.

2003 Volkswagen New Beetle GLS

2002-2003 ENGINE PERFORMANCE Self-Diagnostics - 1.8L Turbo

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Wednesday, December 14, 2005 8:44:34 AM

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