INFINITI M45 (2003-2010) Engine Oil Pressure Switch and Sensor Guide
Is your M45's oil light acting strange? This guide covers everything you need to know about replacing the engine oil pressure switch.
- Always verify your oil level manually before assuming the switch is bad.
- A faulty switch is risky; it can cause panic or fail to warn you of real engine danger.
- Replacement is a simple, low-cost DIY job that can be done in under an hour.
- For this critical part, consider a reputable brand or OEM over the cheapest option for reliability.
Is Your M45 Oil Pressure Switch Failing?
A faulty oil pressure switch can be misleading. It can either cause panic by turning the oil light on for no reason, or create a false sense of security by failing to warn you of a real problem. Given the low cost of the part and the high cost of engine repair, it's a replacement that should not be delayed.
Common Failure Symptoms
- Flickering Oil Light: The oil pressure light on your dash may flicker, especially during turns, acceleration, or braking.
- Incorrect Warnings: The oil light may stay on constantly even when the oil level and pressure are perfectly fine. Conversely, it may never come on, even during the initial ignition-on bulb check.
- Oil Leaks: The switch itself can fail and leak oil. You might notice a small, persistent drip and oily residue on the sensor and the area below it on the engine block.
Warning: Do Not Ignore the Oil Light
Never assume the oil light is just a faulty switch. Always manually check your oil level with the dipstick immediately. If the oil level is good but the light stays on, and you hear any engine ticking, knocking, or grinding noises, stop the engine immediately and have it towed. Driving with low oil pressure can destroy your engine in minutes.
Choosing the Right Aftermarket Part
When replacing a critical sensor like this, part quality matters. While the OEM INFINITI part is the safest bet, several aftermarket options are available that can offer good value. Here’s how they generally stack up for your M45.
| Brand Tier | Brands | Quality & Cost Assessment |
|---|---|---|
| OEM / Premium Aftermarket | Genuine INFINITI, Beck Arnley (Use Caution) | The original INFINITI part (Part No. 25240-4M40E) is the benchmark for fit and reliability. Beck Arnley has historically been known for repackaging OEM parts for Japanese vehicles, but more recent feedback suggests quality can be inconsistent. If you choose this brand, inspect it carefully. Expect to pay more for this tier. |
| Mid-Grade Aftermarket | Standard Ignition (SMP), Walker Products, Facet, Vemo | These brands offer a balance of affordability and function. Standard Ignition and Walker are well-known aftermarket names, but like many brands, quality can be a 'shot in the dark,' ranging from excellent to poor. They are a reasonable choice for a daily driver if OEM is not in the budget, but be aware of the risk. |
| Economy Aftermarket | Global Parts, Rostra Powertrain, other low-price options | While the low price is tempting, these parts carry the highest risk of premature failure or inaccurate readings. Some owners have reported issues with aftermarket parts not even threading into the engine block correctly. For a part that costs less than an oil change but protects the entire engine, skimping is not recommended. |
Pro Tip: Check the Threads
Forum users have noted that the thread pitch on this sensor can be unusual. Before installing a new aftermarket switch, compare it carefully to the old one you removed. Make sure the threads match and hand-thread the new switch to avoid cross-threading the engine block.
Frequently Asked Questions (FAQ)
Where is the oil pressure switch located on the 2003-2010 M45?
The oil pressure switch is located on the engine block, typically near the oil filter. You will need to access it from underneath the vehicle. It is a small sensor with a single electrical connector.
Can I replace the M45 oil pressure switch myself?
Yes, this is a very DIY-friendly job for a home mechanic. It requires basic tools, jacking up the vehicle safely, and takes less than an hour. The main tool needed is a deep-well socket (the exact size can vary, but 24mm is common for similar Nissan/INFINITI engines).
Will a lot of oil come out when I remove the old switch?
No. If the engine has been off for a little while, only a small amount of residual oil (a few ounces) will drip out. It's located high enough on the block that you won't get an 'oil bath'. Place a rag or drain pan underneath to catch the drips.
Should I use thread sealant or Teflon tape on the new switch?
Many new switches come with a pre-applied thread sealant. If yours does not, using a small amount of liquid thread sealant designed for automotive sensors is a good idea for extra security against leaks. Some forum users also use Teflon tape, but ensure it's applied correctly so no tape fragments can enter the oil passages.
Were there any recalls for the M45 oil pressure switch?
No, searches of the NHTSA database show no recalls or technical service bulletins (TSBs) specifically for the engine oil pressure switch on the 2003-2010 INFINITI M45.
Technical Specifications
OEM Part Numbers: 25240-4M40E 25240-4M400
Single pin (1-terminal) connector, threaded base. Typically located near the oil filter housing.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- INFINITI M45: