One of the scariest warnings we can get from our cars is a low oil pressure warning. In most cars that means the appearance of a lil’ red idiot light in the shape of a super old oil canister. Some other cars, however, will scream at you when your oil pressure is low. My 2010 Volkswagen Golf GTI, for example, emits a shrill tone you might hear at a live Justin Bieber concert. This happened to me recently, so I investigated my intermittent low oil pressure light with some very simple tools. In today’s how-to, I will show you how I did it, what tools I used, and what the results were.
(Ed. Note: Working under the hood and under the car is inherently dangerous, so use protection like safety glasses, gloves, and jack stands to keep yourself safe.)
Before we dive in, it’s important to know the difference between the low oil pressure light and the low oil level light. In pretty much all modern cars, low oil pressure is a red light and low oil level is an amber/yellow light. If you see the amber light, check your oil and top it off. Do the same when you see the red light, and that will usually solve your problems. That wasn’t the case in my GTI, though. My oil was topped off, and I was still seeing the occasional flashing red light in super random situations.
For a while, I was sure the light was tripping at random because of a faulty sensor. The light started popping up in unexpected situations like coming to a stop from speed. That, coupled with some VW forum doomscrolling, was my impetus to physically check my pressure numbers. I didn’t have the right tools at home, so I headed to a local tool store to grab a cheapie mechanical oil pressure gauge kit.
I usually spring for the middle-cost option so I can avoid cheap quality and have a good array of adapters with the kit. This Maddox oil pressure gauge kit seemed to do the trick for about $50 and came with a transmission pressure gauge that I literally will never use.
The kit itself is fairly straightforward, but before you get to using that, the first thing you’re going to do is locate your stock oil pressure sensor. It’ll be in random spots like on the engine block on some cars, while others like my GTI will have it close to the oil filter housing.
Before you remove the sensor, however, look up oil pressure specifications for your particular car. Most of the time, you will be measuring hot oil pressure, not cold, which means you’re going to need to get your car up to operating temperature — pro tip: Don’t use the coolant gauge. Oil takes a lot longer to warm up, so put the car through its paces and make sure it’s warm. Different cars have different targets, but generally, 10-20 psi hot is a decent rule of thumb. Some cars may be lower and others higher.
Once you locate the sensor, you can plot your removal. All it takes is unplugging the sensor and using a socket or spanner wrench to loosen and remove it.
I got lucky on my car with the sensor location and didn’t have to worry about burning my hands or arms. Some of you won’t be as lucky so be prepared with long sleeves and some gloves. Remove the sensor, open your testing kit up and start looking at the various adapters until you find one that matches the thread size and pitch of the sensor.
My particular kit had a hose with a quick disconnect from the gauge to make it easier to handle and thread in. Thread the adapter onto the threaded end of the hose and make sure to grab two spanners to counter-hold and tighten the adapter. It will have a tapered thread so it will only take minor snugging.
Once you’ve done that, offer the adapter up to the threaded hole where the oil pressure sensor used to be and start threading it in. Sometimes the hose can get coiled up after a half-turn, so I usually get it started and use the hose itself to thread the adapter in. Once you can’t hand-turn it anymore, grab an open-ended spanner wrench and tighten it down until it bottoms out, or else it will leak.
Attach the gauge to the hose with the quick-disconnect, use the nifty hanger attachment to hang it on the hood, and you’re ready to test. Hop in the car and start it up. If you don’t have an old-fashioned cable throttle-body, it would be best to have a friend help you to test oil pressure at different rpms. I have a newfangled e-throttle, so I enlisted my dad for help.
Once the car is running, make a note of the oil pressure at idle. My car allegedly calls for 20 psi hot but most on the forums report 10-12 psi for the EA888 TSI engine. Next, rev the car up to the rpm specified by your manufacturer and make note of that psi. My car calls for about 40-45 psi at 3,000 rpm, and my car hit it on the nose with 42psi. All checks out here.
Another pro-tip for when you’re checking oil pressure, pay attention to how the needle itself moves. If it is steady and smooth, then all is well, but if the needle is bouncing rapidly at idle or at rpm, that may be indicative of bearing issues or other issues with the oil system.
Now you’re set to check your car’s oil pressure! Go out there and get it done if you’re worried about deeper issues in your engine. Good luck!