BMW Cars 1999-06

Removal & Installation 1

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CAUTION
Engine coolant can spray out causing severe burns if the Engine Coolant Temperature (ECT) gauge sending unit is removed from a hot engine without allowing the engine to cool below 100°F (37°C) and draining the engine coolant into a sealable container first.

  1. Allow the engine to cool below 100°F (37°C) before working on the cooling system.
  2.  
  3. Note the anti-theft code and radio presets for the radio.
  4.  
  5. Disconnect the negative battery cable.
  6.  
  7. Locate the Engine Coolant Temperature (ECT) gauge sending unit as follows:

    S14 engine: In the coolant pipe above the exhaust side of the engine. The rear sensor is for the DME and the forward sensor for the temperature gauge.
     
    M20: engine: On the coolant outlet on the left side of the engine at the junction of the coolant hoses where the coolant flows to the engine block. The DME coolant temperature sensor is the blue colored connector body, the gauge temperature sensor is typically colored brown.
     
    1992-95 E36 models: Under the intake manifold near the front of the engine. The forward sensor (blue) is for the DME and the rear sensor (brown) is for the temperature gauge.
     
    1996-98 E36 models: The coolant temperature sensor for the gauge and the DME control unit is a combined 4 wire, 4 terminal sensor located under the intake manifold near the front of the engine.
     

  8.  
  9. Drain the engine coolant into a sealable container.
  10.  
  11. If additional room is needed:
    1. Remove the air cleaner assembly and the crankcase breather hose.
    2.  
    3. Remove the intake manifold support and pull the wire duct forward.
    4.  

  12.  
  13. On E36 models with a composite spin on oil filter canister cap, remove the canister cap and oil filter and cover the oil filter housing with a clean shop towel.
  14.  
  15. Detach the gauge sending unit electrical connection.
  16.  
  17. Loosen the sensor using a crowfoot wrench, a suitable boxed end wrench or a 7 / 8 inch (22mm) thin-walled 3 / 8 inch drive 12 point deep well socket and breaker bar.
  18.  



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Fig. A suitable prytool used carefully could remove the sensor wiring in an area where fingers couldn't reach-M44 engine shown



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Fig. This Craftsman® 3/8 inch drive thin-walled 12 point deep well socket worked perfectly for removing the coolant sensor



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Fig. The Craftsman® socket slides over the sensor without risking damage to the electrical connector housing



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Fig. The Craftsman® breaker bar and socket combination just cleared the intake manifold and . . .



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Fig. . . . fit over the sensor with plenty of room to loosen or tighten it



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Fig. With the composite oil filter canister top and filter removed, once loosened, the sensor can be removed by hand



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Fig. When installing the sensor, always use a new metal sealing (crush) washer

To install:

  1. Install the sensor with a new crush washer and tighten to 12.5-14 ft. lbs. (17-19 Nm).
  2.  
  3. If removed:
    1. Replace the duct and attach the electrical connector in their original positions. Be sure the rubber grommets are installed correctly to prevent water from entering the duct.
    2.  
    3. Install the intake manifold support and tighten to 15-17 ft. lbs. (20-24 Nm). Install the air cleaner assembly and the crankcase breather hose.
    4.  

  4.  
  5. Top off and bleed the cooling system, reconnect the negative battery cable and re-code the radio as necessary.
  6.  
  7. Start the engine, allow it to reach operating temperature and check for leaks.
  8.  

The Engine Coolant Temperature (ECT) sensors on the S14 engine are located in the coolant pipe above the exhaust side of the engine. The rear sensor services the Engine Control Module (ECM) and the forward services the temperature gauge.

On the M20, 2 sensors are mounted on the thermostat housing. The blue sensor is for the ECM, the brown sensor is for the temperature gauge.

On the M42 engine, the coolant temperature sensors are located under the intake manifold on the engine. The forward most sensor is the ECM sensor and the rear sensor is for the temperature gauge.

On the OBD I M50/S50 engines, the coolant temperature sensors are located under the intake manifold near the front of the engine. The forward sensor is for the ECM and the rear sensor is for the temperature gauge.

On all 1996-98 OBD II 4 cylinder and 6 cylinder engines, the ECM and coolant gauge sensors have been combined into one sensor which is located under the intake manifold near the front of the engine. Terminal positions 1 and 2 are for the coolant gauge and terminal positions 3 and 4 are for the ECM.

  1. Allow the engine to cool. Do not remove the sensor when the engine is warm or hot.
  2.  


CAUTION
Removing the sensor from a warm or hot engine could cause severe burns.

  1. Unplug the ECT sensor's electrical connector.
  2.  
  3. Using a 12 point 22mm ( 7 / 8 inch) thin wall deep well socket remove the sensor by turning it counterclockwise.
  4.  
  5. Remove the sensor along with its sealing washer.
  6.  
  7. Installation is the reverse of the removal procedure, noting the following:
    1. Install the sensor using a new sealing (crush) washer and tighten the sensor to 10 ft. lbs. (14 Nm).
    2.  

  8.  



Click image to see an enlarged view

Fig. The ECT sensor is below the intake manifold and behind the oil filter housing on M44 engines



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Fig. The electrical connector is difficult to reach on some models. A suitable prytool is used to carefully remove the sensor wiring-M44 engine shown



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Fig. Use a 12 point 22mm (7/8 inch) thin wall, deep well socket and a breaker bar to loosen the sensor



Click image to see an enlarged view

Fig. With the ECT sensor's electrical connector unplugged . . .



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Fig. . . . position the socket over the sensor and turn counterclockwise to loosen



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Fig. The 12 point thin wall socket shown beside the sensor



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Fig. Always install the sensor using a new sealing (crush) washer

The sensor can be tested using an ohmmeter either while installed or removed. Removal will require draining the engine coolant. Testing on the vehicle will require the use of suitable jumper leads due to the location of the sensor. The sensor's resistance decreases as the temperature increases (refer to the sensor resistance graph). The measured resistance change for the coolant gauge sensor (sensor terminals 1 and 2 of the M44 sensor) from cold (30°F (-1°C )) to hot (212°F (100°C)) is in excess of 13,000 ohms! When testing the sensor monitor both the measured resistance and the behavior of the sensor as it is tested. Actual readings may differ by as much as plus or minus 10% due to variances of the test equipment (ohmmeter and temperature gauge), though equally important is the sensor's behavior during testing. As the temperature changes the sensor's resistance value should also change. At no time should the resistor develop a completely open or closed circuit. If the sensor's resistance does not change as the test temperature changes, or should the sensor develop an intermittent open or closed circuit during testing, replace the sensor.



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Fig. Actual measured engine coolant temperature sensor resistance values. The coolant gauge uses terminal positions 1 and 2-M44 sensor shown



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Fig. The sensor terminals are labeled but difficult to see. This photo has been enhanced to illustrate the sensor terminal locations-M44 sensor shown


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Access the fault memory of control unit of Digital Motor Electronics (DME), check for any stored fault messages, rectify those faults and clear the fault memory.
  2.  
  3. Remove the cover from injection valves.
  4.  
  5. Unclip the connection for the crankcase venting.

    Click image to see an enlarged view

    Fig. Unclip the connection for the crankcase venting

  6.  
  7. Unfasten the plug connection.

    Click image to see an enlarged view

    Fig. Unfasten the plug connection (1) (illustrated here without intake air manifold)

  8.  
  9. Unscrew and remove the double temperature sensor for Digital Motor Electronics (DME) and coolant indicator.
  10.  

To install:

  1. After returning the temperature sensor back to its position, make sure to vent the cooling system and check for leaks.
  2.  
  3. Reconnect the plug connection.
  4.  
  5. Reclip the connection for the crankcase venting.
  6.  
  7. If necessary, top off the coolant in the reservoir.
  8.  
  9. End by clearing the fault memory.
  10.  


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Disconnect the plug connection (1).
  2.  
  3. Unscrew the temperature sensor.

    Click image to see an enlarged view

    Fig. The removal of the temperature sensor (1)

  4.  

To install:

  1. Reclip the connection for the crankcase venting.
  2.  
  3. If necessary, top off the coolant in the reservoir.
  4.  
  5. End by clearing the fault memory.
  6.  


WARNING
There is a danger of scalding so only perform this task on an engine that has completely cooled down.


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Access the fault memory of control unit of Digital Motor Electronics (DME), check for any stored fault messages, rectify those faults and clear the fault memory.
    NOTE
    For the good of the environment, catch and dispose of any escaping coolant. Research and observe the waste-disposal regulations or laws in your area.

  2.  
  3. Unlock the plug connector (1) and remove it.
  4.  
  5. Release the temperature sensor (2) from its position.

    Click image to see an enlarged view

    Fig. The plug connector (1) and the temperature sensor (2)

  6.  

To install:

  1. After returning the temperature sensor back to its position, make sure to vent the cooling system and check for leaks.
  2.  
  3. If necessary, top off the coolant in the reservoir.
  4.  
  5. End by clearing the fault memory.
  6.  


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Remove the non-return valve on Cylinders One through Six

    Click image to see an enlarged view

    Fig. The non-return valve

  2.  
  3. Disconnect the connector by carefully pulling up on the unit.
  4.  
  5. Remove the temperature sensor.
  6.  

To install:

  1. Make sure to inspect the seal around the sensor, and if it is suspect replace it.
  2.  
  3. Check the coolant level and top it off with coolant, as necessary.
  4.  
  5. Reconnect the sensor by carefully pushing the unit back into its hole.
  6.  
  7. Access the fault memory of control unit of Digital Motor Electronics (DME), check for any stored fault messages, rectify those faults and clear the fault memory.

    Click image to see an enlarged view

    Fig. Reconnect the sensor by carefully pushing the unit back into its hole

  8.  


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Access the fault memory of control unit of Digital Motor Electronics (DME), check for any stored fault messages, rectify those faults and clear the fault memory.
  2.  
  3. Remove the cover from injection valves.
  4.  
  5. Unclip the connection for the crankcase venting.

    Click image to see an enlarged view

    Fig. Unclip the connection for the crankcase venting

  6.  
  7. Unfasten the plug connection.

    Click image to see an enlarged view

    Fig. Unfasten the plug connection (1) (illustrated here without intake air manifold)

  8.  
  9. Unscrew and remove the double temperature sensor for Digital Motor Electronics (DME) and coolant indicator.
  10.  

To install:

  1. After returning the temperature sensor back to its position, make sure to vent the cooling system and check for leaks.
  2.  
  3. Reconnect the plug connection.
  4.  
  5. Reclip the connection for the crankcase venting.
  6.  
  7. If necessary, top off the coolant in the reservoir.
  8.  
  9. End by clearing the fault memory.
  10.  


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Access the fault memory of control unit of Digital Motor Electronics (DME), check for any stored fault messages, rectify those faults and clear the fault memory.
  2.  
  3. For cars with idle-speed control valves, simply unfasten the plug connection to remove the sensor
  4.  
  5. Unscrew and remove the double temperature sensor (1) for Digital Motor Electronics (DME) and remove coolant indicator.
  6.  
  7. For cars without idle-speed control valves, disconnect the vacuum lines and detach the plug from the sensor.
  8.  
  9. Unscrew the sensor.
  10.  

To install:

  1. Make sure to replace sealing ring before installing either type of sensor.
  2.  
  3. After returning the temperature sensor back to its position, make sure to vent the cooling system and check for leaks.
  4.  
  5. If necessary, top off the coolant in the reservoir.
  6.  
  7. End by clearing the fault memory.
  8.  


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Access the fault memory of control unit of Digital Motor Electronics (DME), check for any stored fault messages, rectify those faults and clear the fault memory.
  2.  
  3. Remove the cover from injection valves.
  4.  
  5. Unclip the connection for the crankcase venting.

    Click image to see an enlarged view

    Fig. Unclip the connection for the crankcase venting

  6.  
  7. Unfasten the plug connection.

    Click image to see an enlarged view

    Fig. Unfasten the plug connection (1) (illustrated here without intake air manifold)

  8.  
  9. Unscrew and remove the double temperature sensor for Digital Motor Electronics (DME) and coolant indicator.
  10.  

To install:

  1. After returning the temperature sensor back to its position, make sure to vent the cooling system and check for leaks.
  2.  
  3. Reconnect the plug connection.
  4.  
  5. Reclip the connection for the crankcase venting.
  6.  
  7. If necessary, top off the coolant in the reservoir.
  8.  
  9. End by clearing the fault memory.
  10.  


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Disconnect the plug connection (1).
  2.  
  3. Unscrew the temperature sensor.

    Click image to see an enlarged view

    Fig. The removal of the temperature sensor (1)

  4.  

To install:

  1. Reclip the connection for the crankcase venting.
  2.  
  3. If necessary, top off the coolant in the reservoir.
  4.  
  5. End by clearing the fault memory.
  6.  


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Disconnect the plug connection (1).
  2.  
  3. Unscrew the temperature sensor.

    Click image to see an enlarged view

    Fig. The removal of the temperature sensor and the plug connector (1)

  4.  

To install:

  1. Regardless of its condition, always replace sealing ring.
  2.  
  3. Reclip the connection for the crankcase venting.
  4.  
  5. If necessary, top off the coolant in the reservoir.
  6.  
  7. End by clearing the fault memory.
  8.  


CAUTION
Make sure that the ignition is switched off and no electrical equipment is on or running.

  1. Disconnect the plug connection (1).
  2.  
  3. Unscrew the temperature sensor.

    Click image to see an enlarged view

    Fig. The removal of the temperature sensor (1)

  4.  

To install:

  1. Reclip the connection for the crankcase venting.
  2.  
  3. If necessary, top off the coolant in the reservoir.
  4.  
  5. End by clearing the fault memory.
  6.  

 
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