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Coolant Temperature and Oil Pressure Sensor Replacement
 

Pelican Technical Article:

Coolant Temperature and Oil Pressure Sensor Replacement

Nick Czerula

Time:

1 hour1 hr

Tab:

$50

Talent:

***

Tools:

25mm socket, flathead screwdriver

Applicable Models:

R56 MINI Cooper Hatchback (2007-11)
R56 MINI Cooper S Hatchback (2007-11)

Parts Required:

Oil pressure sensor or coolant temperature sensor

Hot Tip:

Work with a cool engine

Performance Gain:

Remedy gauge issues or fault codes

Complementary Modification:

Replace engine oil or engine coolant

The coolant temperature sensor is a resistor that has a negative temperature coefficient (NTC). This means that the resistance decreases as temperature increases. The resistor is part of a voltage divider circuit that receives 5 volts from the DME. The voltage signal changes depending on engine coolant temperature.

There is a table stored in the DME that specifies the corresponding temperature to each voltage value and therefore compensates the non-linear correlation between voltage and temperature. The resistance changes dependent on temperature from 167 k Ohms to 150 Ohms, corresponding to a temperature from -40 degrees C to 130 degrees C.

The oil pressure sensor (switch) is located on the left front of the cylinder head below the vacuum pump. It consists of a switch, which closes when oil pressure in the engine falls below 0.2 bar (3 psi). When this circuit is closed an output in the instrument cluster is grounded and the warning lamp is illuminated.

When an oil pressure sensor fails, the engine oil pressure light will illuminate or not come on with the key on and engine off. I have seen low engine oil pressure cause similar problems to a sensor, so be sure to test engine oil pressure if you suspect it may be low. Especially do this if you have a flickering oil pressure light.

The oil pressure switch signal is connected to the DME. When the switch is activated 12 volts is sent to the DME. When the switch is not activated 0 volts is sent to the DME.

Oil Pressure Specification

800 rpm: 0.7 bar (10 psi)

3000 rpm - 1.7: 3.0 bar (24.5: 43.5 psi)

NOTE: Oil pressures apply at an oil temperature of 100 degrees C, which is reached after 10-15 minutes driving. 

HOT TIP: CTS and oil pressure sensor connectors are the same. Sometimes these connectors can become brittle and break easily. Now is a good time to replace them. Click here for additional info. 

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

In this article, I'll go over the steps involved with replacing the oil pressure sensor and the coolant temperature sensor on a MINI R56 with a turbocharged N14 engine. Other engines are similar, as the sensors are in the same location. On other engines, remove the intake ducting blocking access to the sensors to replace them.

Working at the crankcase breather-heating element, release the tab (red arrow) and disconnect the electrical connector.
Figure 1

Working at the crankcase breather-heating element, release the tab (red arrow) and disconnect the electrical connector.

Then lift up to detach the hose lock (red arrows) at the valve cover.
Figure 2

Then lift up to detach the hose lock (red arrows) at the valve cover.

Remove the hose from the valve cover (red arrow).
Figure 3

Remove the hose from the valve cover (red arrow).

Working at the vacuum pump, press the brake booster line release tab (red arrow) and pull the vacuum line straight off the pump.
Figure 4

Working at the vacuum pump, press the brake booster line release tab (red arrow) and pull the vacuum line straight off the pump.

Loosen the intake air duct hose clamps (red arrows).
Figure 5

Loosen the intake air duct hose clamps (red arrows).

Remove the intake air duct from the turbocharger, then the intake air housing.
Figure 6

Remove the intake air duct from the turbocharger, then the intake air housing.

On MINI R56 models with a turbocharged N14 engine, the oil pressure sensor (red arrow) is located in the left side of the cylinder head next to the vacuum pump.
Figure 7

On MINI R56 models with a turbocharged N14 engine, the oil pressure sensor (red arrow) is located in the left side of the cylinder head next to the vacuum pump. The coolant temperature sensor is located in the thermostat housing (green arrow) mounted to the left side of the cylinder head.

Working at the left rear of the cylinder head, release the tab and disconnect the camshaft sensor electrical connector (red arrow).
Figure 8

Working at the left rear of the cylinder head, release the tab and disconnect the camshaft sensor electrical connector (red arrow). The intake sensor is shown. If your vehicle has an exhaust sensor, disconnect it too.

Remove the wiring harness housing (red arrow) from the mounting bracket (green arrow) by sliding it straight up.
Figure 9

Remove the wiring harness housing (red arrow) from the mounting bracket (green arrow) by sliding it straight up. Place it aside and out of the way.

The connectors are in a tight spot.
Figure 10

The connectors are in a tight spot. I like to use a 90 degree pick to release and disconnect the electrical connectors. Start with the oil pressure sensor (red arrow).

Then disconnect the coolant temperature sensor connector (red arrow).
Figure 11

Then disconnect the coolant temperature sensor connector (red arrow).

Coolant sensor: You don't have to drain the cooling system.
Figure 12

Coolant sensor: You don't have to drain the cooling system. Just be prepared to catch any leaking coolant beneath the engine and top up the coolant level when done. Using the 90 degree pick again, pull the coolant temperature sensor clip straight out (red arrow).

Coolant sensor: Using pliers, pull the sensor out of the thermostat (red arrow).
Figure 13

Coolant sensor: Using pliers, pull the sensor out of the thermostat (red arrow). If the sealing O-ring does not come out with the sensor, use the pick to remove it from the housing (green arrow).

Coolant sensor: Sometimes the electrical connector cover will remain in the old sensor (red arrow).
Figure 14

Coolant sensor: Sometimes the electrical connector cover will remain in the old sensor (red arrow). If this happens the connector will be exposed and not center in the sensor properly (green arrow). Pull the cover out of the sensor. Then press it back onto the connector (yellow arrow). Install the new sensor with a new sealing O-ring. Use clean engine coolant to lubricate the sealing O-ring. Press it into place. Then install the clip. Top up the coolant and check the coolant level when done. Reassemble the engine components.

Oil pressure sensor: Start by loosening the oil pressure sensor (yellow arrow).
Figure 15

Oil pressure sensor: Start by loosening the oil pressure sensor (yellow arrow). Use a 22mm socket (red arrow) on a ratchet (green arrow) to loosen it.

Oil pressure sensor: Then unscrew the sensor by hand (red arrow).
Figure 16

Oil pressure sensor: Then unscrew the sensor by hand (red arrow). Be sure to replace the sealing washer (green arrow) when installing the sensor again after testing or when installing a new sensor. Top up the engine oil level when done. Reassemble the engine components.

Comments and Suggestions:
airheadearl Comments: @Larry: Sounds like you have a genuinely low oil pressure, I'd change the oil and filter I have seen low oil pressures with the wrong filter installed to make sure you have the right oil in there. Maybe go with Mobil 0w40 to get something a little thicker.
next step: Oil pump, and then I think you're left with rebuilding the engine.
November 16, 2017
  Followup from the Pelican Staff: Thanks for the input on this one. We appreciate the help.
- Nick at Pelican Parts
 
Larry Comments: Just purchased a 2007 Mini S and continue to get low oil pressure alarm. Replaced sensor, no change. Added an oil gauge. Cold it goes to 35 psi then drops to about 3 psi when hot. Engine speed does not seem to have an effect.
Suggestions?
November 13, 2017
  Followup from the Pelican Staff: Sounds like your engine can't make oil pressure. You can try replacing the oil pump. But issue may be in the engine itself. - Nick at Pelican Parts  
Matty Comments: I’ve got an error message showing 2EE2 Coolant temperature sensor plausibility: signal constant. No check engine light at the moment. Does something need attention? I recently changed the exhaust solenoid to get rid of error 2845 and the 2EE2 was there before as well.

I’ve got a Mini Cooper r56. Any tips would be great
October 21, 2017
  Followup from the Pelican Staff: Could be an issue with the sensor or thermostat. I would check engine warm up time, if Ok, replace the sensor. - Nick at Pelican Parts  
airheadearl Comments: My two connectors both fell apart, and I replaced them with the parts listed sort of in the forum link above. I added what I hope is some helpful information about the connectors in the forum.
September 15, 2017
  Followup from the Pelican Staff: Thanks for the additional info and feedback. We appreciate it.
- Nick at Pelican Parts
 
Jake Comments: in the process of replacing my coolant temp sensor. noticed that whoever did the thermostat before I bought the car lost the green cover for the connector. any idea where I could find a replacement?
September 13, 2017
  Followup from the Pelican Staff: It may be available. Give The Pelican Parts parts specialists a call at 1-888-280-7799. They can figure out what part or repair kit you need.
- Nick at Pelican Parts
 
Mike Comments: Upon starting my 07 cooper s the other day whilst leaving work for home, I gave the accelerator a quick throttle while engine was warming up. Idle only increased and idled a bit higher than normal which I thought was strange. Commencing homeward approx one mile on surface street I notice red oil light on. While I have no oil leaks , I always am vigilant about keeping oil level proper and had not gotten oil levels low prior. And my oil level was not low at this time.
I cont. At about 35 mph approx three miles at most and pull into first gas station I see. As soon as I pull in the engine shuts off. While still rolling I attempt to pop clutch to see if it will start. Nada. I start pushing car to parking spot. Parked, I give engine a try by depressing ignition. It would not start. I stop trying, call for a tow.
Upon getting home I give the engine one more attempt via start button. Engine did not turn and in fact it sounded as though starter did not engage flywheel.
Any insight regarding this mystery is appreciated.
September 4, 2017
  Followup from the Pelican Staff: If engine oil level is Ok and the light cam eon, you may have had a loss of engine oil pressure. Your engine could be seized. See if it turns over by hand using a ratchet on the crank pulley. - Nick at Pelican Parts  
Peter 86 Comments: My Radiator fan stop working, i disconnected the temp sensor and the fan came to live. I thougth that my temp sensor was not eorking and repalce it. After connecting all the wires and start the engine, let it warm up and turned on the ac, and the fan did not start. Does it means i need to change the thermostat?
September 3, 2017
  Followup from the Pelican Staff: The low speed portion of fan may be faulty. With no coolant temp, high speed is activated. - Nick at Pelican Parts  
mishmash Comments: 2007 mini n56 r12, showing codes P0014 and P0015. I have replaced both vanos solinoids, both cam sensors, timing chain complete with guides, timing chain tensioner. After short warm up I can shut down and reset the codes, they will return after start up as pending, and will return as full on codes after next start. any thoughts or help would be appreciated.
July 17, 2017
  Followup from the Pelican Staff: Confirm mechanical timing is OK> If so, you may have a fault VANOS actuator / gear on camshaft. - Nick at Pelican Parts  
Chrisw Comments: I have a 2007 mini cooper s it started surging and running bad after i had the thermostat housing changed now it won't idle and is running like crap what could be the problem any help would be appreciated
July 12, 2017
  Followup from the Pelican Staff: I would start by checking the DME for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.
- Nick at Pelican Parts
 
RUGADIAR Comments: I replaced my thermostat with a new coolant sensor. And now my hidden menu shows +++oC. I thought that the new sensor has a failure and replaced with the old one and shows the same +++oC.

Do you now how to show again the temp on the hidden menu? Should i disconnect the battery for a while? Its a MCS 2009.

Thank you.
June 20, 2017
  Followup from the Pelican Staff: I don't have that info. I opened a post in our forums. A Pelican community member may be able to answer your question.
- Nick at Pelican Parts
 
NickB Comments: I recently changed my thermostat housing, water pipe, and water pump. Car is running great but I'm not getting any input from the temp sensor in the hidden menu. Fan runs after the car is shut off for about 5-10 minutes. I had a CEL after the work was completed so I went and had it cleared, after the codes were clear it all was back to normal, but after about 5 minutes of driving the temp signal disappeared from the hidden menu again. Thoughts?
May 6, 2017
  Followup from the Pelican Staff: Not sure, i don;t use the hidden menus. Best bet, use a scan tool, is the engine temp displayed? If so, ignore hidden menu. - Nick at Pelican Parts  
Thom Comments: Excellent guide, thank you very much. Fixed my car for a fraction of the cost. Would be nice to know how to remove the fault codes post completion of the work. Keep up the good work.
April 4, 2017
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
MrAllinder Comments: Getting a oil warning light after 10-15 mins of driving and only after I've come to a stop light or sign. Have replaced the turbo recently with a stock replacement as it blew a seal while driving and the oil pressure sensor. 2 shops have said the oil pump is good. Any idea? 2009 MCS.
March 18, 2017
  Followup from the Pelican Staff: If the oil pump is good, then you have a faulty oil pressure switch or a restriction causing a pressure drop at the switch. I would monitor pressure when the problem is present and see if it does inf act drop. - Nick at Pelican Parts  
Shawn Comments: I recently replaced the thermostat housing, water pump and water pipe but am now intermittently getting CEL with P0118 code. When I use my scan guage tof monitor the coolant temperatur it sometimes drops out of range displaying a temp of -40C. If I wiggle the temp sensor connector the temperature begins to read correctly again. Do you sell new connectors if this is not an issue with the sensor?
March 15, 2017
  Followup from the Pelican Staff: This is the common issue with the sensor...it is actually the sensor that is coming apart inside the housing, usually not the connector. We can get the connector if you want/need one! - Casey at Pelican Parts  
Matthieu Comments: Hi there and many thanks for this great article !

My Mini fan is always running even when the car is cold. I have already changed the coolant temp sensor but the problem still remain. Today with a friend we were able to find a fault code 2F22 - Engine Temperature Signal not plausible however we have no clue what we are supposed to do. Should I change the whole thermostat ?
By the way, I am not able to see the water temp in the "hidden" menu ++++°C. But, we were driving for a test today and all of sudden the coolant temp appeared for a few moments and the fan stop running. Unfortunately, the coolant temp then went away and the fan started again.

Tanks for your help.

Kind regards from Switzerland.

Matthieu.
February 11, 2017
  Followup from the Pelican Staff: Yes indeed change the thermostat. - Casey at Pelican Parts  
delta86d Comments: Recently replaced my thermostat housing. After driving around 20 miles, my CEL came On, p0597, p0173b,p122b. There are no leaks so I just checked the connector going to the ECT sensor and it's just 3.3V. Do you think there is a problem with my ECU? Where would you start if were to troubleshoot this problem? Thanks in advance.
December 17, 2016
  Followup from the Pelican Staff: The harness may be damaged. I would check voltage at the DME to confirm it is low as well. - Nick at Pelican Parts  
Oz Comments: Do you have a "how to" on replacing the thermostat on an 09 JCW?
October 17, 2016
  Followup from the Pelican Staff: See this article:

http://www.pelicanparts.com/techarticles/MINI_R56/89-WATER-Turbocharged_Engine_Thermostat_Replacement/89-WATER-Turbocharged_Engine_Thermostat_Replacement.htm - Nick at Pelican Parts
 
Joe Comments: Hi, I have replaced the oil pressure sensor and oil pump on a 2008 MCS R56 and still have the oil pressure light still on. Any suggestions? Thanks
July 19, 2016
  Followup from the Pelican Staff: What is engine oil pressure at idle and 2500 RPM? - Nick at Pelican Parts  
Goober Comments: I just recently replaced my thermostat housing and associated water pipe, but like a goober I didn't mark the sensor connectors so that I could make certain they go back where they should. Is there a way to tell the oil pressure connector from the water temp one?
June 5, 2016
  Followup from the Pelican Staff: Oil pressure is one wire. coolant is two wires. - Nick at Pelican Parts  
Claude Comments: My temperature gauge is always at max as soon as the key is in the on position on my R50, even first thing in the morning when the engine is definitely cold. I disconnected the sensor and it still reads at max. What part could go bad and cause this issue?
May 12, 2016
  Followup from the Pelican Staff: Either the sensor, wiring or the cluster. Start by testing the sensor signal. Easy way to do it is with a scan tool. - Nick at Pelican Parts  
nitsua Comments: Hi, after replacing the thermostat housing on my R55 08 mini, I kept getting a coolant open circuit code. I could not find any info on locations of sensors anywhere...even my shop manual cd. Finding your sight was fantastic. Excellent descriptions, photos and info on sensors which I am familiar with there operation, just not the locations on this car as I am just starting to work on it..You guys are the best....I cant say enough but I WILL BE BUYING FROM YOU FOR NOW ON....the issue was 2 sensor connectors were switched.....all good now
April 2, 2016
  Followup from the Pelican Staff: Thanks for the feedback. Glad we could help.
- Nick at Pelican Parts
 
rap998 Comments: Some info on how to disconnect the electrical plugs from the sensors would be nice, there seem to be hundreds of different ones used and they are awfully easy to screw up. The plug for the temp sensor is particularly frustrating, as it is so crammed in that you cannot see both sides of the plug to figure out how to release it without damage.
February 18, 2016
  Followup from the Pelican Staff: FOllow the steps until you reach each sensor. The directions on how to release the connector is in the text description next to the sensor. - Nick at Pelican Parts  

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Page last updated: Thu 12/14/2017 02:58:57 AM