Engine Coolant Temperature (ECT) Sensor, Checking
"conceal" code on toEngine Coolant Temperature (ECT) Sensor, Checking
NOTE: Use only gold-plated terminals when servicing terminals in harness connector of sensor.
Recommended special tools and equipment
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram
Test requirements
- Fuses in E-box (in plenum chamber, left) must be OK.
- Ground (GND) connections between engine and chassis must be OK.
- Parking brake must be engaged or else daylight driving lights will be switched on.
- For vehicles with automatic transmission, selector lever must be in -P- position.
- Engine must be cold.
Function test
- Connect diagnostic tester.
- Switch ignition on.
- Under address word 33, select "Diagnostic mode 1: Checking measured values".
- Select the measuring value "PID 05: Coolant temperature".
- Check specified value of coolant temperature:
If specified value is not obtained:
- Continue test according to the following:
Indicated1) Cause
approx. -40 degree C Open circuit or short circuit to B+. Refer to Continuation of Test If Indication Is Approx. - 40 Degrees C. Continuation of Test If Indication Is Approx. - 40 Degrees C
approx. 140 degree C Short circuit to Ground (GND). Refer to Continuation of Test If Indication Is Approx. 140 Degrees C. Continuation of Test If Indication Is Approx. 140 Degrees C
1) If a temperature is indicated which differs greatly from ambient temperature of sensor, check sensor wires for contact resistance.
If specified value is obtained:
- Start engine and let run at idle. The temperature must climb uniformly
NOTE:
- The temperature climbs in increments of 1.0 degree C.
- If the engine shows problems in certain temperature ranges and if the temperature does not climb uniformly, the temperature signal is Intermittent and the sensor should be replaced.
- Switch ignition off