P0521 Code (Symptoms, Causes, How to Fix)

Nothing ruins a drive quite like the appearance of a check engine light (CEL). But far too often, that’s exactly what happens.

As with any CEL, scanning your car for stored trouble codes is the first step. But what if the culprit behind the warning light is a P0521 code?

Let’s look at what a P0521 code means, its possible causes, and how to get it to go away. The good news? In most cases, the fix is fairly simple and won’t cost you too much.

p0521 code

What Does Code P0521 Mean?

OBD-II Trouble Code P0521 Description
Engine Oil Pressure Sensor/Switch Range/Performance

When your vehicle displays a code P0521, it means that there’s a problem with the reading it’s getting from the oil pressure sensor.

Typically, this code occurs when the problem indicates that the sensor itself is faulty, but it’s also possible that the sensor is reporting inaccurate information and is just way off from what it should be.

Finally, it’s possible that the sensor failed and there’s a problem with the oil pressure, so never assume it’s just one problem.

The code is simply telling you that the reading from the engine oil pressure sensor is way off from what it expects, so there’s some sort of problem.

Related: DTC P0520, DTC P0522, DTC P0523, DTC P06DD

Symptoms of Code P0521

While some problems have a variety of symptoms, that’s usually not the case with a code P0521. This code typically only comes with a check engine light, although you might have an oil pressure warning light that illuminates as well.

But don’t take the lack of symptoms as a free pass to keep driving your vehicle. If there is a problem with the oil pressure, you could wind up totaling the engine before you even notice any other symptoms.

Causes of Code P0521

oil pressure sensor
Oil pressure sensor

While there are technically multiple potential causes of code P0521, by far the most likely cause is a bad oil pressure sensor. There are multiple ways the sensor can fail, however, the solution every time is to replace the sensor, so you don’t need to worry about it all that much.

But while a faulty oil pressure sensor is the most common reason for a code P0521, it’s not the only possible reason. Other possible causes include a wiring issue or a faulty power control module, although both these issues are exceedingly rare.

Finally, while it’s unlikely that a P0521 is from low oil or the incorrect type of oil in the vehicle, it is possible. Take the time to check the dipstick before replacing any parts, and consider the possibility of the wrong type of oil if this code appears after an oil change.

Is Code P0521 Serious?

Yes, it’s serious. If your vehicle has a code P0521, you really shouldn’t drive your vehicle, even to the repair shop. This is because your vehicle can no longer warn you if there’s a problem with the oil pressure.

Instead of shutting off the engine or taking other actions to protect the vehicle, if there’s a code P0521, you run the risk of completely totaling the engine if you keep driving. This is especially true if the code comes from low oil or the wrong type of oil in the vehicle.

Play it safe and have a mechanic come to the vehicle to check it out, or tow it to a repair shop so you don’t make the problem worse.

How to Fix

check oil hot or cold

#1 – Check Oil Level

The first thing you should do if you plan on fixing code P0521 yourself is verify the oil level. Pull the dipstick and if there’s low oil top it off, reset the code, then see if the code comes back. Either way, if there’s low oil you need to determine where the oil went.

#2 – Check Oil Pressure Sensor/Switch

If the oil level is correct, connect a high-quality automotive scan tool so you can see exactly what’s happening with the oil pressure sensor. If the sensor appears faulty, replace it, then reset the code and see if it comes back.

If the problem is the oil pressure sensor and you replace it yourself, you can expect to spend $50 to $200, and if you have a professional do it, the cost will be between $150 and $350.

#3 – Inspect Wiring

If the sensor isn’t the problem, we recommend ruling out some basic wiring issues if you have electrical know-how, and if not, you’ll need to take it to a dealership or repair shop specializing in electronic diagnostics.

If it’s a wiring issue, it likely won’t cost much to repair if you can figure it out yourself, but if you need a professional, it’s going to cost a few hundred dollars in labor for diagnosing and fixing it.

#4 – Have PCM Tested/Updated

If you still can’t determine the root cause of your P0521 code, you’ll need to take it to a dealership so they can test, update, or replace the PCM.

This is a worst-case scenario, as the PCM is an expensive component, and the repair will typically cost about $1,000. Fortunately, PCM failure is fairly unlikely but the possibility exists.

#5 – Diagnose Actual Oil Pressure Issue

Finally, if the problem is with the oil pressure itself (low or high oil pressure) there are quite a few potential causes, so you’ll need to narrow that down before you can get an estimate on how much it will cost to repair it. For most people, this isn’t a DIY process so you’ll need to enlist the help of the pros.

Adam Mann

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