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Tanner Fox

Low Oil Pressure, Plnb

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2007 MKZ AWD, suddenly (as in just started today out of the blue) has started showing the oil lamp and low oil pressure message when sitting at idle (around 500-600rpm) and only seems to happen after the engine has warmed up. No odd sounds, no knocking or tapping when the light is on, oil level is right on top of the grid on the dipstick. It's been 10 degrees the past couple of days out, could that do anything? Could the oil pressure sender/sensor act this way? I'm starting to get freaked out already by all of the comments on other forums about other cars saying things like, "Well the engine is probably just worn out and it'll be dead soon  :) ". I've had other strange electrical behavior since it's gotten cold as well on startup like a brief "Check brake system" message that flashes and goes away, usually followed a few seconds later by the airbag light staying on. Shut the car off and turn it back on and all is fine, airbag light goes out. Sometimes when this happens the climate control unit turns off. Could a battery going out cause all of this? Or *gulp* an alternator?

 

https://youtu.be/4ZrlleEJGeg - quick video of it.

 

Edit: Also the title I wrote was "Low oil pressure, plenty of oil". Not sure why it came up with Plnb haha.

Edited by Tanner Fox

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I am going to presume you did check the oil at the dipstick and change it regularly

 

How old is the battery? If it is anywhere near a 5-year life I wouldn't hesitate to put a new one in. ;)

Edited by R2D2

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I am going to presume you did check the oil at the dipstick and change it regularly

 

How old is the battery? If it is anywhere near a 5-year life I wouldn't hesitate to put a new one in. ;)

 

It's been about 3100 miles since the last oil change and as far as I know the last owner took care of this thing since everything is like new. I got the "Works" at the dealership to get the oil/filter changed last time and the battery was tested at factory spec 600cca and it's actual was 500cca, but that was two months ago and the temperature was still in the 40's+. I have no idea what the actual age of the battery is though.

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OIl pressure will drop as engine temp heats up. In an engine with big (bearing) clearances due to wear, that'll cause the pressure to drop too low and trigger the warning.  The only way to make sure it's actually too low or just the sensor is with a gauge.  The pressure sensor is removed and the gauge is screwed in in place of the sensor.  Then the reading is taken with the engine fully warmed up.

 

Here's an example in which an old Ford Fairmont with an easily accessible sensor is used to illustrate the fundamental principle.

 

I see you're at 132K miles.  It's not inconceivable that you have some bearing wear, especially if the previous owner was lax about oil changes.  While it might seem to be well taken care of, do you have any service history on the car?

Edited by drolds1

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It's at 132,000 right now

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I don't have any service records on the car unfortunately.

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So I took the car to the store, spent an hour inside and when I came back out it wasn't showing the oil light at idle in the parking lot or at stop lights. It didn't show it again until I got home and parked. The temp gauge showed the car at operating temp when I started it in the parking lot.

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The temp gauge might be in the middle of the dial but it really takes about 20 minutes of driving before the engine is fully warmed up. 

 

You need to get the actual pressure diagnosed.

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The temp gauge might be in the middle of the dial but it really takes about 20 minutes of driving before the engine is fully warmed up. 

 

You need to get the actual pressure diagnosed.

 

I'll get it pressure tested this week regardless but I'm now even more suspicious of the battery and/or alternator having a say in the problem. So along with the "Check brake system" message, airbag light, climate control being turned off, Navigation unit claiming the DVD was invalid (forgot about this, happened a couple weeks ago), the left HID headlamp didn't turn on when I started the car tonight. Turning the lights off and on brought it on but it's never needed to do that before.

 

Would you or anyone here happen to know by the way where the sensor is located? Normally I don't have a problem with Googling this sort of thing but I can't find much of anything. I'm curious since I don't have a skid plate if something got up onto it after the last snow storm and did some damage but I have no idea what it would even look like. There's a thing that looks like a spark plug on the lower end of the engine block on the left side, kind of in the middle, but I have no idea if that's it.

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How old is your battery?  If it's more than 3 years, it could be on the way out.  I know you said they tested it but it depends on what method was used for testing.  There's an expression that says, "Batteries die in the summer but don't fall over until winter."  These cars do strange things when the batteries get weak, so it's a possibility.

 

WRT the location of the oil pressure sender, it's #9278 in this illustration from Fordparts.com:

 

 

post-5-0-63318500-1513537303_thumb.jpg

 

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It's been about 3100 miles since the last oil change and as far as I know the last owner took care of this thing since everything is like new. I got the "Works" at the dealership to get the oil/filter changed last time and the battery was tested at factory spec 600cca and it's actual was 500cca, but that was two months ago and the temperature was still in the 40's+. I have no idea what the actual age of the battery is though.

There should be a date/date code on the top to help determine the age.

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How old is your battery?  If it's more than 3 years, it could be on the way out.  I know you said they tested it but it depends on what method was used for testing.  There's an expression that says, "Batteries die in the summer but don't fall over until winter."  These cars do strange things when the batteries get weak, so it's a possibility.

 

WRT the location of the oil pressure sender, it's #9278 in this illustration from Fordparts.com:

 

 

attachicon.gifopsender3.5.jpg

 

I had the pleasure of doing the overnight last night so I was able to grab a multimeter out of the maintenance office and see what's up. It was literally 0 degrees F out, car had been driven for just under an hour about 4 hours before I did this: With nothing on, lights/engine/anything, the battery read 12.16v. Car running it read 14.40. So I'm going to assume the alternator is working alright but that sounds like the battery is crap, does it not? 

 

There should be a date/date code on the top to help determine the age.

 

There should be but I couldn't find one. There's a sticker with every month and year on it but it's not filled out, kind of like when you get a pizza box with all of those checkboxes on the side that they don't use.

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I just had similar warning light symptoms with our '96 Cobra (with much fewer computerized sensors and maps). What I thought was a healthy 5-6 year old battery was actually 10 years and 4 months old! 

It measured 12.4 volts at rest, but after cranking a few times I measured 10 volts.  New battery was installed and all is well.

 

The date code was hot-stamped into the plastic on the EDGE of the cover - not visible until I pulled the battery.

 

BTW I credit the 10+ year life of the old battery to use of a Battery Tender during winter months.

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Alright all: The battery has a sticker on it saying B4 so I'm assuming it's only from February of 2014. Not very old. However, the voltages on it tested like it was a piece of garbage to the point that I decided to buy a new battery regardless of the oil pressure issue. I swapped it out yesterday and the car sat until this morning so it's had a good 12+ hours of sitting in the cold. The starter cranked over fast and smooth, nothing electronics-wise had any issues (no errors, no beeping, nothing turning off or flickering while it cranked) and it has stopped complaining about oil pressure. The one it had was a Napa Legend "Premium" and I don't think I will ever buy one of those myself since I've seen a decent number of posts on other forums about them dying after a couple of years which this one apparently has. Thanks everyone!

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Great! I love a simple fix. As I said earlier, these cars' electronics do strange things when the batteries are weak. 

 

Don't feel too bad.  It seems that most batteries are going 3 years max nowadays.  Yours was close to 4 years old.

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Great! I love a simple fix. As I said earlier, these cars' electronics do strange things when the batteries are weak. 

 

Don't feel too bad.  It seems that most batteries are going 3 years max nowadays.  Yours was close to 4 years old.

 

I'm just glad that's all it was. Was starting to get real worried about having a worn engine haha.

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Congrats! Glad it worked out to a quick solution.

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Wait, nevermind! It's now complaining about the oil pressure again.  :(

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:ohsnap:

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Wait, nevermind! It's now complaining about the oil pressure again.  :(

oil pressure light on my '10 mkz was the oil pressure switch. you need to have someone hook a guage up there, and make sure you are getting adequate pressure.

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Final post! Got an actual view of the pressure sensor and it was completely coated in oil. Just covered. The engine is not, no leaking valve covers, everything is as clean as can be so the sensor was definitely leaking. I had the garage swap it out last week and it's been driven daily since with no oil light so I think and hope I'm in the clear.

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