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I recently bought a 2003 Mini Cooper and while driving the oil temperature sensor rises and then goes back down to normal operating temperature, this happens completely randomly there doesn't seem to be any leaks in the coolant system and recently had a new radiator and thermostat. The fan does stay on after shutting off the engine. I'm thinking a faulty sensor. Has anyone experienced this, if so what might be the cause and how would I go about fixing it?
My 2004 pre-facelift R53 (build 10.16.03) began having strange and similar oil temp fluctuation readings after the car was in the shop for a clutch replacement
The dealer installed companion voltage gauge also exhibited weird voltage spikes and odd behavior.
Here is what I later discovered to be the culprit....
Since your Mini is a 2003 - you may have this "ballast" (with cluster of wires connected to it), mounted to the frame (on the left or right side of the engine compartment), secured by a single 10mm nut.
This 10mm nut grounds the ballast and all the wires connected to it.
My 2004 pre-facelift has 2wo - one on each side (L & R) just underneath the hood latch release cables.
I discovered one of the ballast grounding/securing nuts missing. This missing nut caused all sorts of intermittent voltage issues with my gauges.
Check to see if you have this/these "ballast" on your 2003. If the nuts are loose or corroded - clean up the grounding contact surfaces and make sure the 10mm nut is clean, nice and snug.
If you don't have this type of "ballast" - Trace the wire from the oil temp gauge to the oil drain plug and see if there is a loose connection or short. Check it's ground wire (most likely the cause) too for corrosion.
Not sure if I have the answer to your problem.
But I hope it may help you figure it out.
Last edited by Here2Go; Jul 15, 2024 at 07:17 AM.
Reason: added title for clarification
It may not be the answer to your gauge issue - but YEAH; those things could use some good cleaning and good metal to metal ground contact.
You may want to spray some PB blaster or WD40 on those nuts before attempting to remove them to avoid even the slightest chance you may snap the studs/bolts if the nuts are rusted on there.
My 2004 pre-facelift R53 (build 10.16.03) began having strange and similar oil temp fluctuation readings after the car was in the shop for a clutch replacement
The dealer installed companion voltage gauge also exhibited weird voltage spikes and odd behavior.
Here is what I later discovered to be the culprit....
Since your Mini is a 2003 - you may have this "ballast" (with cluster of wires connected to it), mounted to the frame (on the left or right side of the engine compartment), secured by a single 10mm nut.
This 10mm nut grounds the ballast and all the wires connected to it.
Spoiler
The fluctuating oil temperature sensor readings in your 2003 Mini Cooper could indeed point to a faulty sensor or possibly an issue with its wiring or connection. Since you've recently had the radiator and thermostat replaced, and there are no visible coolant leaks, the next step would be to inspect the oil temperature sensor itself. Check for any signs of corrosion or damage to the sensor and its wiring harness. Sometimes, a faulty sensor can intermittently send incorrect signals to the engine management system, causing temperature fluctuations. Replacing the sensor with a new one that matches the specifications for your Mini Cooper should resolve the issue if the sensor is indeed the culprit. If the problem persists after replacing the sensor, further diagnostic testing may be needed to ensure there are no underlying electrical or cooling system issues contributing to the fluctuating readings. I hope this information proves helpful to you. If it doesn't, please let me know, and I'll gladly share more details. I will visit here again. For now, I am gonna visit ucxouri kazinoebi here because I love to play online real money games and with the help of a google search I have discovered that website. I have chosen it because Utskouri Kazinoebi is a comprehensive online resource dedicated to the gambling industry in Georgia. The website offers extensive reviews of online casinos accessible to Georgian players, covering aspects such as game selection, bonuses, and user experience. It also provides news updates on gambling regulations and industry developments, ensuring that players are informed about the legal landscape and latest trends. Additionally, the site includes guides and tips for responsible gambling, helping users make informed and safe gambling decisions.
My 2004 pre-facelift has 2wo - one on each side (L & R) just underneath the hood latch release cables.
I discovered one of the ballast grounding/securing nuts missing. This missing nut caused all sorts of intermittent voltage issues with my gauges.
Check to see if you have this/these "ballast" on your 2003. If the nuts are loose or corroded - clean up the grounding contact surfaces and make sure the 10mm nut is clean, nice and snug.
If you don't have this type of "ballast" - Trace the wire from the oil temp gauge to the oil drain plug and see if there is a loose connection or short. Check it's ground wire (most likely the cause) too for corrosion.
Not sure if I have the answer to your problem.
But I hope it may help you figure it out.
Replying for the updates.
Last edited by JacksonPeterson; Jul 25, 2024 at 10:29 PM.
If those bolts are that cruddy, I would recommend you undo and clean the ground on the passenger side motor mount and check the ground strap as well. It is likely all corroded inside the sheath. (Mine looked fine but I kept having charging issues. I made my own new ground strap with a piece of similar sized wire the issues went away- BTW an oem replacement wire is like $50 so it's significantly cheaper to make your own)
Not the bolts they seemed to be in good condition a little dirty but unlikely the cause, the coolant system was clogged full of sludge and crap so cleared all that out. When undoing the radiator hose i noticed this lose wire under the car this is pictured below, anyone know where this should go
It seems unlikely for an R53 - but that end connector reminds me of an R50 hydraulic clutch slave connector (?).
I've not encountered that wire/connector as of yet on my R53 and I know very little with regards to an R50 - So, I'm sure my preceding comment is way off.
I would be very interested to know what that is myself.
Thanks for the confirmation on the mystery connector.
(I'll be replacing my oil pan gasket in the future and will have to move the AC compressor out of the way. With my luck this wire/connector may become unplugged and I'll also wonder where it came from).
With regards to the oil gauge fluctuation anomaly - Did you ever find a loose or break in either the wire to the sending switch or grounding wire?
Thanks for the confirmation on the mystery connector.
(I'll be replacing my oil pan gasket in the future and will have to move the AC compressor out of the way. With my luck this wire/connector may become unplugged and I'll also wonder where it came from).
With regards to the oil gauge fluctuation anomaly - Did you ever find a loose or break in either the wire to the sending switch or grounding wire?
No, but the coolant system was full of crap, I think as the previous owner used a poor quality cap for the reservoir so grit and sand got into the system. A flush and some new coolant seemed to sort the problem out. Nice cheap fix, fortunately. Will be replacing the coolant reservoir with an OEM one as soon as payday comes
