Having a warning light appear on your car’s dashboard is never something you want to have to deal with, but it is a normal part of owning a vehicle.
An OBD-II code can be used to get a clear diagnosis of what’s going on, but finding out what the specific error code you are getting signifies is only half the battle.
You also need to be able to understand what it means as far as issues and potential fixes go so that you can start taking steps to get the problem repaired.
Here is a quick breakdown of error code P0521.
What Does The P0521 Code Mean?
The P0521 code stands for “Engine Oil Pressure Sensor/Switch Range/Performance.”
The P0521 code indicates that your PCM detects an issue with the engine oil pressure or oil pressure gauge readings or performance.
The latest vehicles contain a PCM/ECM. It uses to control the functionality of the engine sensors and some other electronic parts. The PCM gets data from different sensors and utilizes this data to ensure the optimum performance of the engine.
The engine oil pressure is one of the most important engine sensors. This sensor measures how much mechanical oil pressure is present inside the engine and sends this data to the PCM.
The PCM of the vehicle utilizes this data and tells the driver about the oil pressure in one of two methods. Some vehicle models have a gauge on the dashboard to indicate the oil pressure, while some vehicles contain a warning light that starts illuminating when the oil pressure is less or more than the specified limit.
When your PCM notices a problem with the performance of the engine oil pressure sensor, it triggers the P0521 code.
What are the Possible Causes of the P0521 Code?
Many issues can trigger the P0521 engine code. Below are just some causes of this trouble code. Note that since there are a lot of causes, you need a proper diagnosis to address the issue correctly and efficiently. When in doubt, consult a mechanic or technician.
- Low engine oil level
- Low oil pressure because of internal engine wear
- Defective oil pressure sensor
- Disconnected or faulty wiring in the oil pressure circuit
- Defective oil pump
- Incorrect oil filter (see “Other Notes” below)
- Sludge buildup inside the engine restricts oil flow
- PCM problems (e.g., outdated software)
What are the Common Symptoms of the P0521 Code?
There are several telltale signs of the engine code P0521. If you’re dealing with this specific trouble code, your vehicle may exhibit more than one symptom listed below.
- Check engine light is flashing
- Misfiring
- Hard to start the engine, or the engine won’t start at all
- Engine stalling
- Engine noise, such as ticking, thudding, knocking, or rumbling
- The oil pressure gauge reading is too low or too high
Is Code P0521 Critical?
On its own and with early diagnosis, P0521 is a moderately critical fault code. However, by no means should it be ignored.
Driving with low oil pressure can be very dangerous.
It may ignite your check engine light and require immediate attention. You may not even get any error code, but the oil pressure issue will affect your internal engine parts.
In worst-case scenarios, you may face engine failure. So, it’s best to regularly monitor your car’s engine oil pressure and oil level and get any P-code errors fixed ASAP.
Before that, how is it diagnosed?
How To Diagnose Code P0521?
As with all P-code errors, your mechanic will start their diagnosis with a visual inspection of the engine. They’ll check for the following things:
- Low oil level
- Old dirty oil
- Defective oil filter, oil pump, or drain plug
- Oil pressure switch problems
- Loose electrical connector or faulty wiring at the sensor using a digital Ohm meter
- Oil pressure sending unit and oil switch for loose or faulty wiring
After this checklist, your mechanic will check for any other p codes your engine may have pulled. This helps them determine any leaks within the oil pan, drain plug, or the sending unit.
Finally, your mechanic will check the oil pressure value using a mechanical oil pressure tester to ensure that it’s in the specified range.
So now that you’ve diagnosed the problem, how do you fix it?
How Is Fault Code P0521 Fixed?
Most times, once your mechanic has narrowed down the problem, they will perform the following repairs:
- Replacing old dirty oil with the correct oil viscosity
- Resetting the oil sensor to check if the problem persists
They will also compare your PCM’s engine oil pressure readings to another oil pressure scan tool. This will indicate whether there’s a problem with your PCM or oil pressure sensor. If that’s the case, you may need a new pressure sensor.
Once the mechanic rules out the possibility of a problem with your PCM, they may need to replace and repair any damaged wiring and loose connections. This includes cleaning the oil pan and oil filter and replacing the sending unit, oil switch, or oil pump.
Now that we have that out of the way, let’s look at other queries about fault code P0521.
Common P0521 Code Diagnostic Mistakes
- Replacing the oil pressure sensor without inspecting other parts.
- Not clearing the powertrain control module storage after fixing the issue.
P0521 Code Repair Cost
The repair cost of code P0521 depends on the vehicle model and the parts that need to be repaired. To fix this code, you need to repair or replace one or more of the following parts:
| Parts | Cost |
|---|---|
| Oil filter replacement | $30 to $80 |
| Oil replacement cost | $15 to $70 |
| Oil pan replacement | $650 to $750 |
| Oil pressure sensor replacement | $120 to $150 |