BMW 5251 Service Manual page 446

I
Fuel lniection
varies as the coolant temperature (sensor resistance) chang-
es.
NOTE-
The ECT sensor is an NTC (negative temperature coeff-
cient) type sensor. In other words, as the temperature rises,
resistance through the sensor decreases.
If the ETC sensor input is faulty or non-plausible, the MILis il-
luminated when OBD II fault criteria are exceeded. The ECM
assumes a substitute value (8OoC/176"F) to maintain engine
operation. The ignition timing is set to a conservativelsafe ba-
sic setting.
4
Disconnect ECT sensor harness (A)
-
Checlc ECT sensor resistance using a multimeter at sensor
terminals 3 and 4. Peel back protective boot (B) to ID termi-
nal numbers on connector housing.
/
ECT sensor resistance
@ l
2O" C (68°F)
2.2
-
2.7
kd
WARNING
-
Due to risk of personal injug be sure the engine is cold be-
fore disconnecting ECT harness connector.
Sensor replacement: Disconnect ECT sensor harness (A).
-
Unscrew ECT sensor from cylinder head and install new sen-
sor.
Use new copper sealing washers when installing sensor.
Replace any lost coolant.
Tightening torque
ECT sensor to coolant flange 13
Nm
( I 0
it-lb)