Hello. I posted here a couple of years ago regarding an intermittent oil pressure light in my 2006 R53 Cooper S HT. I've been getting an intermittent oil pressure light on, mostly when accelerating, then it goes out when the throttle is released.

Oil has always been full. In fact, I've never had to add oil between changes. (35k miles total).

The light had not been acting up for about a year but I started noticing it again. Dealer service manager said it could be wiring chafing. I think he's right, but I can't find the source.

I verified that it is in the wiring. I started with the wiring diagram. It's a very simple circuit. There are no relays in the oil pressure circuit. There is one wire (hot from the dash indicator lamp) to the sensor. The sensor is normally closed (light on) but oil pressure in the sensor opens the circuit. Thus, any short in the wiring to ground will be the same as the circuit closing due to low oil pressure.

The sensor works normally. That is, key on, engine not started, light is on. Engine started, light goes out at idle. Light does not come on again until car is moving, particularly when accelerating. Light goes out when throttle is released. This indicates that the fault is sensitive to movement of the engine on its mounts. The light does not seem RPM sensitive. The light will come on when cruising down the freeway at 3,000 RPM, at idle, or any RPM in between, but generally when there is a transition or change of speed.

I verified that it is not low oil pressure by disconnecting the sensor. I got the same exact behavior of the light, except that it then does not come on with the key on and engine not running. Since I'm driving the car with the sensor disconnected, and the light is going on and off, I know that the operation of the light is not related to oil pressure.

I checked the wiring by putting the car on a pair of Rhino ramps. I inspected the wiring from above as much as I could by removing the upper exhaust heat shield. I inspected from below by removing the power steering pump cooling fan. I did not see any obvious chafing although the harnesses were tightly zip-tied together above the starter where I really couldn't see very well.

Has anybody else had this same problem and found a source of wiring chafing? Given my analysis above, I'm certain that the problem is in the wiring and is not a mechanical problem with the engine. The engine is running and sounds fine otherwise.

Thanks for any help you can provide.

 

Change the sensor?
Maybe attach a mechanical guage to be 100% sure....
Hate to have a fault in the base of the filter in the bypass that is causing a real issue...

 

PS
If it is a wiring issue...
Have one person watch the light...
And have another wiggle the wires...should see it happen...

 

+1

My local independent MINI tech tells me he is seeing bad sending units on a number of MINIs lately.

 

@Zippynh

I knew people would come up with answers like, "check your oil" and "put a mechanical pressure gauge on it".

With the sensor disconnected, the light goes off and on while driving the same way as when it's connected. It has to be the wiring.

The suggestion of wiggling the wire while someone (my wife) watches the light is a good one and one I considered already. I'll probably give that a shot this weekend. Not much of the wire is really accessible, however, at least without removing the engine. But maybe that will narrow down where the short is.

I'm hoping someone has had the exact same problem and can advise where the short was found.

 

Did you tape up the plug when you unplugged the sender? If it was somewhere that it could have touched ground while you were driving, that might give your test false readings.

 

If you were to see the plug you would see that there are no exposed contacts and no chance for the plug to ground itself to anything while disconnected.

The problem is definitely in the wiring, but it could be anywhere between the plug and the connection on the back of the dash indicator light.

I'm hoping someone has had experience with this same problem. I've reviewed the other posts in this forum, and haven't found an answer yet.

 

Did you ever resolve this problem, my mini 2013 s is have the same issues.