Low Oil Pressure Advice Needed.
Thread Starter
Race Director
Joined: Apr 2007
Posts: 13,007
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From: Happiness is Busch in Victory Lane!
St. Jude Donor '09 & '12, '14
Low Oil Pressure Advice Needed.
Tonite I fired up my 2001 C5 MN6 and headed for a cruise.
My oil pressure guage is always pegged on 80 and the DIC reads 130psi (Bad sensors I assume)
I was driving fairly normal to my destination 10miles away..went to 4k rpms a few times.
on my return back I stopped at a traffic light and took off pretty solidly (4k rpm) and the dreaded Ding happened and my DIC said "Low Oil Pressure" "Service Engine Soon" The Oil Pressure guage which is always pegged at 80 since i owned it dropped to zero then climbed again to 80. All the warning lights went away.
I kept going a little further ( as the engine sounded totally normal ) and under some minor acceleration the warning lights went on again - The guage dropped to zero "Low Oil Pressure Service Engine soon" and back up to 80 with all lights going away.
I drove low RPM's (Under 2k) all the way home (8 miles) and right before my home I gave it a little gas in 2nd gear (went 20-40mph quickly) and sure enough!! "Low Oil Pressure" "Service Engine soon" As always the engine sounds normal.
What could be causing this?
My oil pressure guage is always pegged on 80 and the DIC reads 130psi (Bad sensors I assume)
I was driving fairly normal to my destination 10miles away..went to 4k rpms a few times.
on my return back I stopped at a traffic light and took off pretty solidly (4k rpm) and the dreaded Ding happened and my DIC said "Low Oil Pressure" "Service Engine Soon" The Oil Pressure guage which is always pegged at 80 since i owned it dropped to zero then climbed again to 80. All the warning lights went away.
I kept going a little further ( as the engine sounded totally normal ) and under some minor acceleration the warning lights went on again - The guage dropped to zero "Low Oil Pressure Service Engine soon" and back up to 80 with all lights going away.
I drove low RPM's (Under 2k) all the way home (8 miles) and right before my home I gave it a little gas in 2nd gear (went 20-40mph quickly) and sure enough!! "Low Oil Pressure" "Service Engine soon" As always the engine sounds normal.
What could be causing this?
Instructor
Joined: May 2002
Posts: 242
Likes: 2
From: Fort Washington MD
Low oil pressure
Better check your oil pressure and be safe. I had the low oil pressure light come on and I thought maybe the sending unit is bad. There was no engine noise at the time. I did not drive the car but purchased the unit. The next day I started the car and heard noise from the drive train and shut it down. I am replacing my oil pump this week end. Some early C5 oil pumps have been known to fail with out warning. Good luck
Thread Starter
Race Director
Joined: Apr 2007
Posts: 13,007
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From: Happiness is Busch in Victory Lane!
St. Jude Donor '09 & '12, '14
Better check your oil pressure and be safe. I had the low oil pressure light come on and I thought maybe the sending unit is bad. There was no engine noise at the time. I did not drive the car but purchased the unit. The next day I started the car and heard noise from the drive train and shut it down. I am replacing my oil pump this week end. Some early C5 oil pumps have been known to fail with out warning. Good luck
Good Idea. I will be taking it in to get the above mentioned fixes done. I believe it to be an oil pump. Correct me if I'm wrong but if the problem is happening only on acceleration then the oil pump is not keeping up with demand? Or the pegged to 80 sensor decided to start dropping to zero every time I accelerate with any bit of force. Driving at Low RPMS crippled is no issue...I'd hate to think false readings go off due to some electrical issue...
However, I'm looking for a likely cause prior to the dreaded trip to the dealership. I have an extended warranty - looks like it covers oil pumps but maybe not sensors.
Thanks again for any advice.
Thread Starter
Race Director
Joined: Apr 2007
Posts: 13,007
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From: Happiness is Busch in Victory Lane!
St. Jude Donor '09 & '12, '14
With 45 days ownership I'm just beginning to fix the common c5 problems I've been reading on here. Car is totally stock and not raced.
I had just finished 2/3 of my detailing so I could post my newb pictures on here when i went for the infamous ride above...
After coming home crippled with my wife doing this
I told her as I pulled into the driveway "The only thing worse could be if the column lock problem happens right now"
As I said I'm slowly working the common problems!!
Le Mans Master
Joined: Sep 2003
Posts: 6,276
Likes: 227
From: Farmington CT
Cruise-In VII Veteran
you have a bad sending unit, when you turn the key on, the gages sweep, the oil pressure remains at 80 psi prior to start, just need to swap the oil pressure gage, you motor is fine
very common problem
very common problem
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Team Owner
Joined: May 2006
Posts: 21,473
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From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
Check your oil level(Of course!)
And get a new sender as soon as possible! and hook it up! Sounds as if the oil pressure sending unit is fully out of whack at this time!
Please let us know what you find and when you fix it!
If there is enough oil and it is not low the sender has got to be the problem!
Did you check to see if the sender cracked and let the oil out spewing it on the ground? (Just thinking outloud!)
Thanks,Matt
And get a new sender as soon as possible! and hook it up! Sounds as if the oil pressure sending unit is fully out of whack at this time!
Please let us know what you find and when you fix it!
If there is enough oil and it is not low the sender has got to be the problem!
Did you check to see if the sender cracked and let the oil out spewing it on the ground? (Just thinking outloud!)
Thanks,Matt
Burning Brakes
Joined: Dec 2004
Posts: 1,067
Likes: 3
From: Lost in the Pine Barrens with only ketchup and relish packs, New Jersey
If the oil level is ok and the pressure gauge is at 80, the sender under the intake is bad- very common as others have posted. PS- Don't replace it with the GM part, use the standard auto ps308 unit. I did and had better success with it in the past. Good Luck! 
Thread Starter
Race Director
Joined: Apr 2007
Posts: 13,007
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From: Happiness is Busch in Victory Lane!
St. Jude Donor '09 & '12, '14
Check your oil level(Of course!)
And get a new sender as soon as possible! and hook it up! Sounds as if the oil pressure sending unit is fully out of whack at this time!
Please let us know what you find and when you fix it!
If there is enough oil and it is not low the sender has got to be the problem!
Did you check to see if the sender cracked and let the oil out spewing it on the ground? (Just thinking outloud!)
Thanks,Matt
And get a new sender as soon as possible! and hook it up! Sounds as if the oil pressure sending unit is fully out of whack at this time!
Please let us know what you find and when you fix it!
If there is enough oil and it is not low the sender has got to be the problem!
Did you check to see if the sender cracked and let the oil out spewing it on the ground? (Just thinking outloud!)
Thanks,Matt
I have just never seen anyone post that they got Low oil pressure from the sender unit. all previous posts I have read show the classic symptoms of pegged at 80. The low oil pressure only happens on acceleration (not low rpm driving). I agree with you the sensor could be out of whack now and doing both. I'm taking it now and the repair will begin Monday.
I'll let you know about this Low oil pressure problem!
Le Mans Master
Joined: Sep 2003
Posts: 6,276
Likes: 227
From: Farmington CT
Cruise-In VII Veteran
