I'm hoping someone can help ... I am a "new" owner of an '02 530i E39 (prod. 01/02).
Autozone scanned because my SES light came on and they said it's the coolant temp. sensor... but I can't find where the thing is. There are also two sensors - square with 2 connectors and round with 4 connectors.
Most of the CTSs I've seen on other vehicles are located in the block somewhere - but I don't see one on the block. The guy at A/Z said it's by the oil filter - but there are two there - the first one is the oil sensor - I pulled it out and could see the oil on it. The other one is extremely difficult to reach, so I figured I would check here first but I can't find anything that identifies where the CTS is ...
Thanks in advance.
Last edited by jamesdc4; 12-29-2009 at 09:18 PM.
I don't mean to step on your toes James but the temperature sensor that most commonly fails in this case would be item number 4. I checked the sales history and we have replaced 7 sensors through the shop and sold 4 over the front counter in the past month. It is in the lower rad hose about 2.5" away from the rad right under the expansion tank. The part number is 13-62-1-433-077.
James - in looking at the engine, I can't even see the sensor shown in the diagram - even using mirror. If there is a sensor there, BMW must have held it in a jig and built the car around it - LOL.
FWIW: the dash guage works fine, but since it got cooler (in AZ) I've noiticed that the air from the heating vents is not very warm ... not sure how this relates (sorry for not including that in the first place).
Max - I think you're right - rather than trusting AutoZone (as another poster so eloquently put it - there's a reason those guys work THERE) I think I am going to run by one of the local independent BMW shops to at least diagnose what the real problem is.
Thanks to everyone - I'll let you know what it turns out to be.
Last edited by jamesdc4; 12-29-2009 at 10:31 PM.
Max is correct. You can't just take someone from Autozone literately. My guts feeling is you need a new thermostat for your car.
Call me crazy, but it looks like BMW's don't like cold weather.
Hi,
I also had BMW& AZ check the SES code, BMW wants to replace the termostat but the gauge reads fine.
AZ read me the code message (coolant temp below thermostat setting)
I think the thermostat is working fine & controlling the temp, the coolant sensor that reads the temp is bad but I don't know which one is (item 4 on previous tread?)
Thanks,
It could be the thermostat, the water inlet temp or outlet temp sensors or a problem with the engine ecu, but the electrically heated thermostat is a common problem.
The thermostat is partially electrically controlled from the engine ecu and gets inputs from radiator inlet and outlet temps, engine load and speed, throttle opening etc.
The error "coolant temp below thermostat setting" probably means that the engine ecu controlled temp setting is not being met as the actual water temp is lower than that which the engine ecu is asking for.
The thermostat has an inbuilt heater as well as the usual wax/spring arrangement. The engine ecu controls the heater part to assist with the thermostat opening and closing. The M54 and M52TU engines can and do operate at up to approx 109Deg C (others say up to 113 Deg C) under light load conditions to reduce emissions.
The temp gauge shows normal over a wide operating temperature range so just because its showing mid range/normal doesn't mean the thermostat is working correctly. The thermostat heater part may be faulty but the wax/spring part will still work to control the temp and this temp may still be within the normal range of the temp gauge but outside the temp the engine is aking for.
Hope this helps.
RonR
99 528iT M52TU
Thanks Aussie528iT
After posting my message, I took the car for 20 minutes of higher RPM/speed driving, after restarting the engine the SES light went off.
My wife drives this car only about 5 miles each way so the engine does not get to operating temp often, but this light just came on recently.
I understand that the ECU is looking at temp over time so something is has changed, I don't want to spend time/money changing the wrong thing.
The SES lite has been off for 2 days now.
Thanks again,
Mo
Does anybody know what the RESISTANCE reading of a good TEMP SENSOR is.. what Ohm value? This is the TEMP SENSOR going to aux fan? How do I know its bad. AUX FAN doesnt come on.
THANKS SCOTT
For an M54 or M52TU engine there are 2 more temp sensors as well as the one in the lower radiator hose.
No 13 here. http://www.realoem.com/bmw/showparts...01&hg=11&fg=30
No 3 here.
http://www.realoem.com/bmw/showparts...69&hg=11&fg=15
RonR
I am a strong proponent when it comes to proper diagnosis, measuring resistance (Ohm) to rule out bad temp sensors etc., I don't like to waste money on part I don't need.
But...in your case, the main culprit is the temp sensor, which has a service life of about 8-10y/100K or so. A new temp sensor is about $22.
For $22, install new sensor and move on with your life. Change the sensor only when coolant is cold. Apply a tiny smear of grease on the O-ring before install. Do a quick swap (get the new part ready) so you don't lose much coolant.
Last edited by cnn; 06-27-2010 at 12:54 PM.
I believe we may have the same problem. The code for this description is P0128 and the description says (engine coolant temp is below normal).
I just got the "Engine Failsafe Prog" and I just replaced the blown fuse. Temp gauge is now working properly too. I'll order a new coolant temp sensor tomorrow. Thanx for the lead.
Digging up the old thread.My temperature gauge is slightly below normal.Just replaced the themostat,but still the reading is the same.Could it be the temparature sensor which is located in the engine block?E39 M52 1996.
One low quality picture.
Last edited by 316driver; 10-08-2010 at 06:03 AM.
E39 523i;E46 316i
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