P0521 – Meaning, Causes, Symptoms, & Fixes - FIXD

What Does Code P0521 Mean?

• P0521 definition: Engine Oil Pressure Sensor/Switch Range/Performance
• Issue Severity: SEVERE – Stop driving immediately
• Repair Urgency: Fix this code immediately (same day if possible) to avoid internal engine damage.
• Diagnosis: Initially, this trouble code will not stop your vehicle from operating normally. However, if not addressed early on, this code can cause serious internal damage to your engine causing complete engine failure. It is recommended to take your vehicle to the nearest dealership as soon as possible to have this code properly repaired to avoid costly engine repair(s).

The oil pressure sensor calculates the oil pressure of the vehicle’s engine. This is then communicated to the ECM in the form of a voltage value. The P0521 code is set when the ECM detects the voltage value is either higher or lower than the specified acceptable range of oil pressure. This code can also be set when the engine detects constant fluctuation of the oil pressure value.

P0521 Causes

There are many potential causes of code P0521.

• Faulty oil pressure sensor (sometimes called an oil pressure sending unit)
• Faulty wiring/connections
• Short or open ground in the wiring
• Blown Fuse
• Engine coolant temperature sensor is not operating correctly
• Faulty Power Control Module

P0521 Symptoms

• Check engine light
• Oil pressure warning light
• Oil pressure gauge too high/low
• Engine stall

How Do I Fix Code P0521?

With an oil pressure sensor fault, the first step is to get it diagnosed to figure out what is causing the problem. 

If your vehicle has this fault and you’re not comfortable diagnosing this issue at home, we recommend finding a RepairPal certified shop nearby to pinpoint the problem and give an accurate estimate for repairs. 

These shops can not only help you figure out what’s going wrong before you waste time and money on the wrong parts, but they also offer a minimum 12-month, 12,000-mile warranty and stand behind all their estimates with guaranteed fair pricing.

> Find a RepairPal Certified Shop Near You

How Much Does It Cost to Fix Code P0521?

P0521 can be caused by anything from a low oil level to a bad oil pressure sensor to a leak or clog in your oil lines. It’s impossible to give an accurate estimate without properly diagnosing the issue first. 

If you take your car to a shop for diagnosis, most shops will start with an hour of “diag time” (the time spent in labor diagnosing your specific issue). Depending on the shop’s labor rate, this typically costs somewhere between $75-$150. Many, if not most, shops will apply this diagnosis fee to any required repairs if you have them perform the repairs for you. From there, a shop will be able to give you an accurate estimate for repairs to fix your P0521 code.

Possible Repair Costs for P0521

For error code P0521, one or more of the below repairs may be needed to solve the underlying issue. For each possible repair, the estimated cost of repair includes the cost of the relevant parts and the cost of labor required to make the repair.

• Top off oil: $5 to $10
• Oil and filter change: $136 to $149
• Oil pan replacement: $654 to $740
• Oil pressure sensor: $123 to $140

DIY Steps to Diagnose Code P0521

Engine code P0521 could be caused by a number of things, including a bad oil pressure sensor, clogged oil lines, or just a low oil level. If you’d like to try to fix code P0521 at home without throwing money at parts, you’ll want to follow the steps below for proper diagnosis. Keep in mind this is an intermediate-level diagnosis and repair and not recommended for beginners. Diagnosis requires more specialized equipment beyond what the FIXD Sensor can provide and it can be a time and labor-intensive process for inexperienced DIYers.

DIY difficulty level: Intermediate

This repair requires mechanical knowledge and is not recommended for beginners.

Tools/parts needed (our top picks from Amazon):

• FIXD

STEP 1: USE FIXD TO ENSURE NO OTHER ENGINE CODES ARE PRESENT.

Use FIXD to scan your vehicle to verify P0521 is the only code present. If other codes are present, they must be addressed first.

STEP 2: CHECK OIL LEVEL.

Use the dipstick to check the oil level of your vehicle. It should be between the Full and Add markings on the dipstick.

STEP 3: CHECK OIL FILTER AND DRAIN PLUG.

Verify the oil filter and drain plug are secure with no leakage. A leaky drain plug can be caused either by the plug itself, or damaged threads where it screws into the oil pan. In this case, the entire oil pan may need to be replaced.

STEP 4: INSPECT OIL PRESSURE SENSOR WIRING.

Visually inspect the wiring around the oil pressure sensor for disconnected or damaged wires.

STEP 5: CHECK OIL PRESSURE SENSOR VOLTAGE.

Using FIXD Live Data, check the oil pressure sensor voltage to ensure that it is within the specified range.

STEP 6: REPLACE OIL PRESSURE SENSOR.

If the problem persists, consider replacing the oil pressure sensor.

Common P0521 Diagnosis Mistakes

Prematurely replacing the oil pressure sensor without visually inspecting the wiring of the oil pressure circuit for disconnection or damaged wires.

Still Need Help Fixing Code P0521?

If you’ve followed the steps above and are still experiencing check engine code P0521, please contact the FIXD Mechanic Hotline if you’re a FIXD Premium subscriber or find a RepairPal certified shop near you to get the right repairs at a fair price.

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