2EF4 code with Service Engine Soon
#1
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My Ride: 2006 530xi touring
Model Year: 2006
Engine: 3 liter
2EF4 code with Service Engine Soon
I got the SES light and it was time to service the cooling system (194,000 miles) so I changed out the water pump and the thermostat. The SES light came back in a few days with the code 2EF4 (mechanical thermostat fault).
I actually do not know what else can be bad? I will change out the coolant temp sensor today but is there anything else to check?
I actually do not know what else can be bad? I will change out the coolant temp sensor today but is there anything else to check?
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My Ride: 05 530i M54
Model Year: 05 530i
Engine: 3.0 M54
That sounds like the engine harness issues the 8cyls had years ago. Hopefully it doesn't come down to that or you'll be trying to find a cheap harness.
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My Ride: 528i
Model Year: 2010 528i e60
Engine: N52k
Is the engine temperature and coolant temperature where is should be (with the new pump and thermo)?
Is the new thermo operating as it should?
Its always possible the new thermostat is malfunctioning.
A while back I called the product manager for Pierburg that makes my water pump. He told me the reason those pumps and thermo's go bad is owners use the wrong coolant or don't mix it properly.
Is the new thermo operating as it should?
Its always possible the new thermostat is malfunctioning.
A while back I called the product manager for Pierburg that makes my water pump. He told me the reason those pumps and thermo's go bad is owners use the wrong coolant or don't mix it properly.
#5
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My Ride: 2006 530xi touring
Model Year: 2006
Engine: 3 liter
I did a bit of troubleshooting today. Hooked up my Launch scanner and started the engine at idle. For more than 10 minutes, the Coolant Temperature at Engine and Coolant Temperature at Radiator Outlet climbed slowly to 52C and 47C respectively. That means (to me) thermostat is stuck open and does not allow engine temp to raise to operating temperature. It should get to 75C or 80C in 10 minutes (??)
I will crawl under the check for 12V at the Thermostat connection, and if not there, try to find a fuse for that Tstat line. Where is that fuse?
If 12V is there, then I have to assume that the new Thermostat fails right out of the box.
Although the SES light was there BEFORE the thermostat was swapped, so chances are the problem is with the car, not the part.
I will crawl under the check for 12V at the Thermostat connection, and if not there, try to find a fuse for that Tstat line. Where is that fuse?
If 12V is there, then I have to assume that the new Thermostat fails right out of the box.
Although the SES light was there BEFORE the thermostat was swapped, so chances are the problem is with the car, not the part.
#6
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It can take a while to get the coolant up to spec, especially if it's a cool(ish) day. I'd try cranking the AC to max to help it along.
But yeah, if the thermostat is "stuck open" it's going to take forever or longer to come up to full temperature. I suppose that's a possibility with the N52 thermostat (assuming it's controlled by the DME rather than having a simple (and reliable...) metallic spring to turn the coolant flow on and off. But to make up for the unnecessary complexity, BMW helpfully mounted it where it's really, really difficult to replace. ;-)
And the other relevant question is - what brand is the thermostat? There are a lot of no-name options that I wouldn't trust, especially for a part this integral to the longevity of the engine, and due to the PITA factor for replacing it. Also, there are a host of counterfeit parts floating around, so if you got it from anything other than a well-trusted source, you could have a no-name thermostat (that came in a BMW box).
But yeah, if the thermostat is "stuck open" it's going to take forever or longer to come up to full temperature. I suppose that's a possibility with the N52 thermostat (assuming it's controlled by the DME rather than having a simple (and reliable...) metallic spring to turn the coolant flow on and off. But to make up for the unnecessary complexity, BMW helpfully mounted it where it's really, really difficult to replace. ;-)
And the other relevant question is - what brand is the thermostat? There are a lot of no-name options that I wouldn't trust, especially for a part this integral to the longevity of the engine, and due to the PITA factor for replacing it. Also, there are a host of counterfeit parts floating around, so if you got it from anything other than a well-trusted source, you could have a no-name thermostat (that came in a BMW box).
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I got the SES light and it was time to service the cooling system (194,000 miles) so I changed out the water pump Tutuapp 9Apps Showbox and the thermostat. The SES light came back in a few days with the code 2EF4 (mechanical thermostat fault).
I actually do not know what else can be bad? I will change out the coolant temp sensor today but is there anything else to check?
I actually do not know what else can be bad? I will change out the coolant temp sensor today but is there anything else to check?
Last edited by Seth dustin; 05-21-2023 at 03:33 AM.
#8
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My Ride: 2006 530xi touring
Model Year: 2006
Engine: 3 liter
I will need to wait til tomorrow to measure the voltages. I am too busy today putting an engine back in a Ferrari F355 F1.
The T-stat is a Mahle-Behr version, and bought from Pelican so all are good names. Plus, the SES light went on BEFORE I swapped out the Thermostat so I am thinking it's with the car, not the Thermostat. That thermostat is in a really inconvenient spot to work on. What stupid designer did this ?
The T-stat is a Mahle-Behr version, and bought from Pelican so all are good names. Plus, the SES light went on BEFORE I swapped out the Thermostat so I am thinking it's with the car, not the Thermostat. That thermostat is in a really inconvenient spot to work on. What stupid designer did this ?
#9
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My Ride: 2006 530xi touring
Model Year: 2006
Engine: 3 liter
OK,
1. Ignition ON, engine OFF, Thermostat connector disconnected, there is 12V on one pin, and 4V on the other pin (this is likely the pin from the ECU that is an open collector circuit).
2. Ignition OFF, engine OFF, thermostat connector disconnected, the 4V signal goes to zero since there is no more electrical current any where
3. Engine on and running, thermostat connector Plugged back in, the pin that was 4V before now bounces around from 12V to zero and then steadies out at >13V (battery voltage when car is running)
All I can conclude is the main ECU is controlling the thermostat by turning it on and off at start up. The thermostat seems to be dead (out of the box).
Since it is only $100 ish, I will replace it and see where we are.
1. Ignition ON, engine OFF, Thermostat connector disconnected, there is 12V on one pin, and 4V on the other pin (this is likely the pin from the ECU that is an open collector circuit).
2. Ignition OFF, engine OFF, thermostat connector disconnected, the 4V signal goes to zero since there is no more electrical current any where
3. Engine on and running, thermostat connector Plugged back in, the pin that was 4V before now bounces around from 12V to zero and then steadies out at >13V (battery voltage when car is running)
All I can conclude is the main ECU is controlling the thermostat by turning it on and off at start up. The thermostat seems to be dead (out of the box).
Since it is only $100 ish, I will replace it and see where we are.
Last edited by donpb; 05-23-2023 at 07:08 PM. Reason: Spell check
#10
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My Ride: 2006 530xi touring
Model Year: 2006
Engine: 3 liter
I found this video on line explaining how it works.
he showed the thermostat has failed in the Closed position. I had thought that it was designed to fail in the Open position so that the engine won't overheat. Comments anyone?
he showed the thermostat has failed in the Closed position. I had thought that it was designed to fail in the Open position so that the engine won't overheat. Comments anyone?