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HOMESERVICE MANUALSAUDI1999A4 BASE, 1.8 B, AUTOMATICREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCESYSTEMENGINE CONTROLS - SELF-DIAGNOSTICS - 1.8L TURBODIAGNOSTIC TESTSDTC P0116/16500, P0117/16501 & P0118/16502: ECT SENSOR CIRCUIT FAILURE
1999 Audi A4 Base, 1.8 B, Automatic

DTC P0116/16500, P0117/16501 & P0118/16502: ECT Sensor Circuit Failure

1999 Audi A4 Base, 1.8 B, AutomaticSECTION DTC P0116/16500, P0117/16501 & P0118/16502: ECT Sensor Circuit Failure
  1. Inspect Engine Coolant Temperature (ECT) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was okay, go to next step. If sensor connector was repaired, erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article.
  2. Turn ignition off. Disconnect ECT sensor 4-pin connector. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/22 test box to PCM wiring harness. Using DVOM, check resistance between ECT sensor connector terminals and specified test box sockets.
    • ECT sensor connector terminal No. 1 and test box socket 53.
    • ECT sensor connector terminal No. 3 and test box socket 67.

    Resistance should be 1.5 ohms or less. If resistance is within specification, go to next step. If resistance is not within specification, repair open wiring harness as necessary. Erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article.

  3. Using DVOM, check resistance between specified terminals.
    • ECT sensor connector terminal No. 1 and ground.
    • ECT sensor connector terminal No. 1 and test box socket 67.
    • ECT sensor connector terminals No. 1 and 3.
    • ECT sensor connector terminal No. 3 and ground.

    Resistance should be infinity. If resistance is infinity, go to next step. If resistance is not infinity, repair short in wiring harness as necessary. Erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article.

  4. Using a DVOM, check voltage between ECT sensor 4-pin harness connector terminal No. 1 and ground, then terminal No. 3 and ground. Voltage should be zero volts. If voltage is as specified, go to next step. If voltage is not as specified, repair wiring harness as necessary. Erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article.
  5. Using a DVOM, check resistance between ECT sensor terminals No. 1 and 3. See ECT SENSOR RESISTANCE table. If resistance is to specification, erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article. If resistance is not to specification, replace ECT sensor. Erase DTC memory. See CLEARING CODES in SELF-DIAGNOSTICS - INTRODUCTION article.
ECT SENSOR RESISTANCE

Temperature Ohms
86°F (30°C) 1500-2000
176°F (80°C) 275-375
RENDER: 1.0x

NO RELATED

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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  • • The engine overheats, stalls repeatedly, or misfires under load.
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