Skip the auto shop - Our mechanics make house calls

Q: The oil pressure is fine but when I crank the car and when it warms up it drops down to maybe 20 and starts knocking a little. Whats wrong?

asked by on

Is it oil pump or pressure sensor

My car has 161407 miles.
My car has an automatic transmission.

The first step is to check the level of the oil. Assuming it’s full, and there are no leaks on the system, it could be the pump or the sensor. The easiest way, despite that you need a special tool, is to hook up a gauge inline and test the oil pressure. This will allow you to see if you truly have a pressure issue or if the electronics are to blame. This gauge will replace the oil pressure sensor/switch. Remove the switch, thread in the sensor (carefully, and snugly), and start the vehicle. If the pressure is below the ratings for your vehicle, and the oil level is full, you will want to replace the pump. You will also want to make sure the passages are clean and sludge free. Bent, damaged, or clogged oil lines can also cause pressure issues. If the pressure is where it needs to be, the issue is the sensor and it should be replaced.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  • Home
  • Questions
  • The oil pressure is fine but when I crank the car and when it warms up it drops down to maybe 20 and starts knocking a little. Whats wrong?

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Starts fine then after a minute or so starts to misfire.

Hi there. Check the oil pressure to the fuel injectors and see if the pressure is dropping. The injectors require the oil pressure to make them work and if the pressure is dropping, then the injectors will not fire. If...

Q: Why is my truck running rough. 2000 Chevrolet S10

Hello. Rough running can be caused by a number of things. To determine where the issue is I would usually start by scanning the computer for codes. This would help me determine if the issue is at a particular cylinder....

Q: The car won't start

Hi, thanks for writing in. Usually, when you hear a single click, it means that the starter is bad. A good diagnosis of this is taking a small wrench or hammer and knock on your starter a few times. If...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.