DTC P0116/16500 - ECT Sensor Circuit Range/Performance Problem

NOTE: DTC is set as soon as coolant temperature is less than 131°F (55°C) after engine start, but 18 minutes later temperature has not risen to more than 158°F (55°C).

Inspect Engine Coolant Temperature (ECT) sensor connector for looseness and/or corrosion. Repair sensor connector as necessary. If sensor connector was not repaired, go to next step. If sensor connector was repaired, erase DTC memory and test drive vehicle. See CLEARING CODES and TEST DRIVE in TESTS W/CODES - INTRODUCTION article.

Turn ignition off. Disconnect ECT sensor connector. Using a DVOM, check resistance between ECT sensor terminals No. 1 (signal) and 3 (ground). See ECT SENSOR RESISTANCE table. If resistance is to specification, go to next step. If resistance is not to specification, replace ECT sensor. Erase DTC memory and test drive vehicle. See CLEARING CODES and TEST DRIVE in TESTS W/CODES - INTRODUCTION article.

ECT SENSOR RESISTANCE

Temperature	Ohms
68°F (20°C)	Approx. 2500
176°F (80°C)	Approx. 330

Turn ignition off. Disconnect Powertrain Control Module (PCM) connectors. Connect VAG 1598/19 test box to PCM wiring harness. Terminal assignments of test box are identical to PCM connectors "A", "B", "C", "D" and "E".
Using DVOM, check resistance between ECT sensor connector terminal No. 3 and engine ground. Resistance should be a maximum of one ohm. If resistance reading is within specification, go to next step. If resistance reading is not within specification, repair open or short circuit between ECT sensor connector terminal No. 3 and engine ground. Erase DTC memory and test drive vehicle. See CLEARING CODES and TEST DRIVE in TESTS W/CODES - INTRODUCTION article.
Using DVOM, check resistance between ECT sensor connector terminal No. 1 and test box socket 16A. Resistance should be a maximum of one ohm. If resistance reading is within specification, go to next step. If resistance reading is not within specification, repair open or short circuit between ECT sensor connector terminal No. 1 and PCM connector "A" terminal No. 16. Erase DTC memory and test drive vehicle. See CLEARING CODES and TEST DRIVE in TESTS W/CODES - INTRODUCTION article.
Check ECT sensor connector terminals No. 1 and 3 for shorting to each other. If circuits are shorting to each other, repair as necessary. Erase DTC memory and test drive vehicle. See CLEARING CODES and TEST DRIVE in TESTS W/CODES - INTRODUCTION article. If circuits are not shorting to each other, replace faulty PCM. Code new PCM and test drive vehicle. See PCM CODING and TEST DRIVE in TESTS W/CODES - INTRODUCTION article.