Parts Catalog Accessories Catalog Tech Info Tech Forums
 
Follow Pelican Parts on Facebook Follow Pelican Parts on Twitter Follow Pelican Parts on Instagram Follow Pelican Parts on YouTube Follow Pelican Parts on Pinterest Follow Pelican Parts on Tumblr
  Search our site:    
View Recent Cars  |   Cart  | Project List | Order Status | Help    
Get FREE Ground Shipping with the purchase of $75 in qualifying parts!
 

Bookmark and Share

 


Pelican Technical Article:
Radiator Outlet Temperature
Sensor Replacement


Nick Czerula

 
Time: 1 hours
Tab: $60
Talent:  
Tools:
T20 Torx driver, Flathead screwdriver
Applicable Models:
325i (2006)
325Xi (2006)
330i (2006)
330xi (2006)
328i (2007-2009)
335i (2007-2009)
Parts Required:
Engine coolant, radiator outlet temperature sensor
Hot Tip:
Work with a cool engine.
Performance Gain:
Repair faulty sensor or remedy coolant leak
Complementary Modification:
Replace radiator hose
 
   

   

Check out some other projects in this series: 

Need to buy parts for this project?
Click here to order parts for your BMW from our parts catalog
   
     BMW E90 models utilize a radiator outlet temperature sensor that’s located in the right side radiator hose. The sensor monitors coolant temperature as it leaves the radiator. The sensor reading is used by the DME to determine when the electric cooling fan is activated. The sensor can fail electrically, a fault code will be stored and the MIL (malfunction indicator lamp) will be illuminated. The sensor can also leak coolant from the sensor sealing O-ring. I have replaced this sensor and soon after developed a leak at lower radiator hose. If it’s in your budget, replace the lower radiator hose also as preventative maintenance. Replacing the radiator outlet temperature sensor is a snap and can be done working above engine on right side of radiator.
The radiator outlet temperature sensor might be the cause of a hard to find coolant leak.
Figure 1
The radiator outlet temperature sensor might be the cause of a hard to find coolant leak. The sensor is mounted in a plastic section of the right side radiator hose. There is a sealing O-ring that normally prevents leaks in the system. Over time, this O-ring fails and creates a coolant leak. At first, it will be a small leak and you may notice a small amount of coolant under the right side of your vehicle or the coolant reservoir coolant level slowly dropping. This photo shows the beginning of a failing O-ring. You can see coolant seeping out through the sensor mounting bung (green arrow). If you have a small, yet hard to locate coolant leak, start by inspecting this sensor. Lift and support front of vehicle safely. See our tech article on lifting your BMW E90. Remove engine splash shield. See our tech article on splash shield removing. Drain cooling system. See our tech article on draining and filling your cooling system.
Large Image | Extra-Large Image
Working at front of radiator support, remove two T20 Torx fasteners from the intake duct.
Figure 2
Working at front of radiator support, remove two T20 Torx fasteners from the intake duct. (green arrows)
Large Image | Extra-Large Image
Working at intake air duct connection on air filter housing, using a small flathead screwdriver, release retaining tabs on each side and pull duct off.
Figure 3
Working at intake air duct connection on air filter housing, using a small flathead screwdriver, release retaining tabs on each side and pull duct off. Normally-aspirated engine shown. For turbocharged engines, the duct on the radiator support unscrews the same as the previous step, the duct for the air filter housing is also removed the same way, the air filter housing is in a different spot. Follow duct and release tabs to remove duct.
Large Image | Extra-Large Image
Then, pull intake duct out of radiator support and remove from vehicle.
Figure 4
Then, pull intake duct out of radiator support and remove from vehicle. (green arrow)
Large Image | Extra-Large Image
Radiator outlet temperature sensor is located on the right side of radiator, installed in the radiator hose.
Figure 5
Radiator outlet temperature sensor is located on the right side of radiator, installed in the radiator hose. (green arrow) Clean area on hose around sensor. You want to remove any dirt or debris that could go into sensor mounting bung when sensor is removed.
Large Image | Extra-Large Image
Working at radiator outlet temperature sensor, disconnect electrical connector by pressing wire release tab (green arrow) and pulling off.
Figure 6
Working at radiator outlet temperature sensor, disconnect electrical connector by pressing wire release tab (green arrow) and pulling off.
Large Image | Extra-Large Image
To remove sensor from hose, squeeze plastic locking tabs on sensor (green arrows) and pull sensor out of radiator hose.
Figure 7
To remove sensor from hose, squeeze plastic locking tabs on sensor (green arrows) and pull sensor out of radiator hose. Be prepared to catch any excess dripping coolant in a container when you pull sensor out of hose. I like to keep my drain pan under the area of the hose. To install new sensor, lubricate sensor O-ring with clean engine coolant. Then push into radiator hose until both plastic mounting tabs engage. Then connect electrical connector and reassemble intake air duct. Fill and bleed cooling system. See notes on bleeding below. Bleeding cooling system: Trapped air is common when filling a cooling system and can result in improper cooling. It is important to bleed your cooling system each time the cooling system is serviced. Install expansion tank cap and be sure all bleeder screws are tight. Turn ignition ON (do not start engine), set temperature controls in vehicle interior to full warm and blower fan speed to Low. Press accelerator pedal to floor and hold down for ten seconds. Electric coolant pump will run for about 12 minutes to circulate coolant and bleed air from cooling system Once pump has run the cycle, check level of coolant in expansion tank and adjust as needed. Start and run engine at idle until it reaches operating temperature and check cooling system for leaks.
Large Image | Extra-Large Image
Need to buy parts for this project?
Click here to order parts for your BMW from our parts catalog
Bookmark and Share
Comments and Suggestions:
jomega Comments: Hey there, I followed this guide thanks for the write up, I wanted to inspect the sensor and I noticed something.. the piece I pull out looks different than the sensor I see everywhere.... is this sensor 2 different pieces? because the entire sensor didn't come out, the electrical connector slid out connected to a much thinner piece with a smaller o-ring.. I'm wildly confused.. the 2 tabs stayed in place when i pulled the piece that I'm referring to out of the car..
August 21, 2014
Jny0511 Comments: Hello, Nick. My 2006 325i runs fan at maximum speed when I just turn on the engine in cold weather. I thought that it was the temperature sensor, but I do not see any fault code on the dashboard display. What would be the cause?

The other thing is that I got stuck at Figure 7 above. I press the two taps and pulled the sensor, but sensor was still stuck and I could not get it out. I figure that the tap on the top pressed in still did not unlock the locking mechanism in the holes just below the taps. Any help or any tool recommendation are appriciated. Thank you.
July 28, 2014
  Followup from the Pelican Staff: There may be dirt or debris preventing the sensor locking tabs from releasing. Try cleaning the area around the sensor, the top specifically and seeing if it releases.

What does the engine temp in a scan tool read? There may not be a fault, but you could have a faulty sensor. - Nick at Pelican Parts
 
mule Comments: Bmw year 1998,model 3181 engine e194 4cylinder can not start.pluged the diagnostic modue.it was sho wing oxygen sensor after catalyic convetor and coolant outlet sensor.can this cause the vehicle not to start.plse help.
May 4, 2014
  Followup from the Pelican Staff: Not likely. I can't help without knowing what is missing from the system when you are trying to start it. When your engine doesn’t start you’ll want to check the basics. Check spark, fuel injector pulse and pressure fuel, volume and quality. Are there any fault codes? Once you figure out what is missing, it will be easier to diagnose.
- Nick at Pelican Parts
 
altronbm Comments: No fault code. The fan run at maximum speed when the engine just get warm. Engine run good and very quiet in cold weather. When I have noise, I unplug the aux. fan, the noise go away. I think I need to replace coolant temperature sensor, but I could not locate the sensor same as show in fig. 7. Where is a sensor in the cylinder head you refer?
January 6, 2014
  Followup from the Pelican Staff: See attached photo. It is located at the front of the cylinder head, left side. - Nick at Pelican Parts
altronbm Comments: Hello Nick, I have 2007 328I and need to replace coolant temperature sensor. But I don't see any sensor attach to the radiator hose same as show in Fig. 7both left & right side. I like to locate the sensor before buy new one. Could you please help? Thanks
January 2, 2014
  Followup from the Pelican Staff: Do you have a fault code? It could be for the sensor in the cylinder head. - Nick at Pelican Parts  
Cliff55 Comments: Sorry, Nick. Called one of the BMW guys at Pelican and he said you were referring to the right of the driver. Therefore, I was looking at it the wrong way.
December 18, 2013
  Followup from the Pelican Staff: The right side of the vehicle is always the right as you sit facing forward. Thanks - Nick at Pelican Parts  
Cliff55 Comments: Nick, like the article. Exactly what I have been looking for. However, my sensor appears to be on the left side. Unless, I am looking at the wrong sensor.
December 17, 2013
  Followup from the Pelican Staff: The right side of the vehicle is always the right as you sit facing forward. Thanks - Nick at Pelican Parts  

Check out some other sample projects from the book: 

 

Got more questions?  Join us in our BMW Technical Forums

Or, see what other questions readers have asked about this article...
  Applies to: 325i (2006), 325Xi (2006), 330i (2006), 330xi (2006), 328i (2007-2009), 335i (2007-2009)
  Search our site:    

View Cart & CheckOut | Project List | Order Status |  Help    

 

[Home] [Customer Service] [Shopping Cart] [Privacy Statement]
 [Contact Us] [About Us] [Shipping] [Map to our Location]

Copyright © Pelican Parts Inc.