RepairSmith offers upfront and competitive pricing. The average cost for Mercedes-Benz E420 Oil Pressure Sensor Replacement is $146. Drop it off at our shop and pick it up a few hours later, or save time and have our Delivery mechanics come to you.
We perform over 600 repair and maintenance services including oil changes,
brakes, diagnostics, belts and hoses, and more. The best part?
We come to you with all the necessary tools and parts.
What Are The Common Symptoms Of A Faulty Oil Pressure Sensor?
If your vehicle has a bad oil pressure sensor, you’ll encounter one or more of these symptoms:
1. The Oil Pressure Light Turns On Or Starts Blinking
Your vehicle’s oil pressure warning light usually turns on when the oil pressure sensor (or oil pressure switch) detects a high/low oil pressure and alerts the ECU (Electronic Control Unit) or PCM (Powertrain Control Module).
That’s standard practice.
However, say your engine oil level looks okay, but the oil pressure light on the dashboard cluster stays on or blinks constantly — that could mean your oil pressure sensor is about to go out, or worse, already defective.
2. Inaccurate Oil Pressure Gauge Readings
An older vehicle with a mechanical oil pressure gauge may show inaccurate readings when the sensor is faulty. For example, a gauge reading “0” at the correct engine oil level can indicate a bad oil pressure sensor.
On the flip side, oil gauges in modern cars communicate with sensors via electrical signals.
If your modern car has a bad sensor, your oil pressure gauge will show strange, often extreme, readings — like full oil pressure or zero oil pressure.
3. Noisy Engine And Timing Chain
The tensioners holding your engine’s timing chain in place are usually oil-fed.
When the oil pressure drops, the loosened chains whip around and get thrown against the pulleys and housings. That produces a deep, distinctive, metallic rattling noise from the engine block.
If you hear the noise, but the oil light doesn’t illuminate, your vehicle’s oil pressure sensor has likely gone bad.
4. Oil Leak From The Oil Pressure Sensor
Oil may leak from a faulty oil pressure sensor when your engine is idling.
Since your oil pressure sensor is seated in the oil system, oil sometimes leaks from the sensor’s threads or through its center.
If you notice an oil leak around the sensor or inside it, your sensor is damaged and needs replacing.
How Much Does An Oil Pressure Sensor Replacement Cost?
An oil pressure sensor replacement can cost around $100-$130.
This average cost splits into:
Cost of replacement parts: it ranges between $50 and $60, depending on whether you pick aftermarket or OEM (Original Equipment Manufacturer) auto parts.
Cost of labor: the labor cost will vary based on whether you take the vehicle to a dealership, auto repair shop, or hire a local mechanic.
Keep in mind that this estimate doesn’t factor in your location and vehicle make. Moreover, if your mechanic recommends additional repairs or purchasing other car parts, the cost will increase.
How Urgent Is An Oil Pressure Sensor Replacement?
As a general rule, never ignore any symptoms of a bad oil pressure sensor.
Ideally, you should stop driving the car and avoid restarting the engine until a professional mechanic diagnoses and resolves the issue.
That’s because a defective engine oil pressure sensor will fail to warn you of low oil pressure in the engine. If that happens, your engine may no longer be able to keep itself properly cooled or lubricated and can seize up.
The result is irreversible damage to critical components and increased future repair costs.
4 Oil Pressure Sensor FAQs
Let’s explore a bit more about oil pressure sensors through some commonly asked questions:
1. What Is An Oil Pressure Sensor?
An oil pressure sensor (a.k.a. an oil pressure switch, oil pressure sender, or oil pressure sending unit) is a component that monitors the oil pressure inside your vehicle’s engine.
Based on the method of operation, there are two types of oil pressure monitoring devices:
Sensors: a sensor is essentially a pressure transducer whose internal resistance changes with fluctuating oil pressure.
Switches: the electrical switch closes when your vehicle’s oil pressure drops below a certain threshold specified by the automaker.
When your engine oil pressure is low, the oil pressure sensor or oil pressure switch signals the vehicle’s ECU or PCM. Without the oil pressure sender, there’s no way of knowing if the oil flow is enough and if your engine gets appropriately lubricated.
In short, an oil pressure sending unit helps guarantee the safe operation of your vehicle.
2. How Does An Oil Pressure Sensor Become Defective?
An oil pressure sensor/switch has three parts:
A port open to the oil passage
A rubber, steel, or ceramic diaphragm
A sensor or electrical contacts
Typically, your oil pressure sensor becomes faulty when the diaphragm gets damaged. For example, the rubber diaphragm can rupture over extended use, causing the oil to leak and flood the sensor or electrical contacts.
The pressure transducer or electrical contacts can sometimes fail even when the diaphragm stays intact.
3. How Do I Get A Faulty Oil Pressure Sensor Diagnosed?
When you take the car to a mechanic, suspecting an issue with the oil pressure sensor, they will:
Check your engine oil level first. If the oil pressure light is on, but the engine oil level is fine, your oil pressure sensor isn’t working right.
Start your engine and check the oil pressure with a mechanical oil pressure gauge. If the pressure isn’t low but your oil light illuminates, you’ve got a bad sensor.
Visually inspect the oil pressure sender for signs of oil leaks, poor connections, or damaged wires. If they notice any defects, the sensor is probably due for replacement.
Measure the resistance of your vehicle’s oil pressure sensor when the engine is at rest and see if it falls within the acceptable range specified in the repair manual. If not, your oil sensor is faulty.
4. How Do I Replace A Bad Oil Pressure Sensor?
The exact steps for replacing your defective engine oil pressure sensor will vary depending on the make and model of your vehicle.
While you may be able to replace the oil pressure sensor on your own, it’s not recommended. The risks associated with an improperly installed oil pressure sensor make it inadvisable as a DIY project.
That’s why we’ll provide a general walkthrough of the oil pressure sensor replacement process, as how a mechanic would perform it.
First, your mechanic will gather all the equipment/tools they’ll need for the job — a jack, jack stands, a special oil pressure sensor socket, safety glasses, a torque wrench, a ratchet, an oil pan, and so on.
Disconnect your vehicle’s negative battery cable.
Raise the car with a jack and support it on jack stands.
Locate the engine oil pressure sensor/switch.
Disconnect the electrical connector from the oil sensor.
Loosen your oil pressure sensor with a special socket, ratchet, or torque wrench.
Remove the defective oil pressure sensor.
Compare the old sensor with the new sensor to confirm compatibility.
Coat the new sensor’s thread with a sealant.
Install the new oil pressure sensor.
Tighten the sensor with a special socket, ratchet, or torque wrench.
Lower the vehicle and remove the jack stands.
Start the car and confirm that the oil pressure warning light has gone off.
Check if the engine oil level is proper.
Start the engine and listen for any rattling noises from your engine block.