Happy new year all members, driving back from holiday I noticed my oil pressure light in the gauge cluster does not show up when turning the key to ON. It used to work before because I usually notice 4 red lamps (battery, oil, CEL and handbrake) but one was missing.

I checked the oil and was all fine, car runs fine and no CEL codes. At home I took the gauge cluster out to see if the bulb was burned but also that is not the case, all bulbs are fine.

The car is a 1999 impreza MT (1.6). What could this be, the send not making contact properly? where is the sender located?

Thanks for your replies.

Usually the pressure switch is kind of underneath the alternator. Normally it is just a single push on connector on it, very easy to pull. Then you could check if the light is on with that wire disconnected, and how it is if you ground that wire.

Usually the pressure switch is kind of underneath the alternator. Normally it is just a single push on connector on it, very easy to pull. Then you could check if the light is on with that wire disconnected, and how it is if you ground that wire.

 

You simply mean pull the wire and ground it directly to the engine block (ground as in connect). The light should then come on since it is in a loop circuit. I assume the reason the light is on with engine off is because there simply is no pressure.

Right, before engine cranking, the pressure switch would be at its shelf state, so the light would be on.

 

So basically, if, by unhooking the lead and grounding it and then leaving it unhooked completely, you are able to make the light turn on and off, then it is possible the pressure switch is faulty.

Pulled the wire from the sensor and measured the resistance over the sensor, nearly 0 Ohms. So sensor was ok, bit of sweat, I hate wire problems in a car!! (who does not). So grounded the wire to the block, and light is on.

Scratched a bit on the contact point and now it is fine. Weird so suddenly.

It sounds like it is working now? It might have just not had a good connection at the connector that plugs onto the pressure switch spade.

Is this sensor location, a good place to try a manual gauge? If yes, What are normal pressures for a 99 2.2? (warm idle) ever since I changed TB & waterpump & all pulleys, & changed oil /filter, (10w30Castrol & OE filter)Seems like there's a slight thunking at idle, & more noticeable when put in drive. (due to lower rpm?) Old oil was nasty from the PO, maybe they doctored oil up to hide sound for me, the sucker?

Yes that spot is perfect to connect a pressure gauge.

Warm Idle, ~700rpm, pressure of 10-12psi or more is normal. At 3,000 rpm you should see at least 35 - 40psi.

 

When it's cold you should use 5w-30 for better oil flow at start-up. You really should just use it year round unless you live in a very hot climate where you need the higher temp viscosity of a 40 grade oil. Even better for winter would be a 0w-30 or 0w-40 oil which would flow better still than 5w, but that's not necessary unless you live in an area that routinely sees negative double digit temperatures.

Yes that spot is perfect to connect a pressure gauge.

Warm Idle, ~700rpm, pressure of 10-12psi or more is normal. At 3,000 rpm you should see at least 35 - 40psi.

 

When it's cold you should use 5w-30 for better oil flow at start-up. You really should just use it year round unless you live in a very hot climate where you need the higher temp viscosity of a 40 grade oil. Even better for winter would be a 0w-30 or 0w-40 oil which would flow better still than 5w, but that's not necessary unless you live in an area that routinely sees negative double digit temperatures.

 

Thank you, & I agree about the 5w-30, but I have 144k on odo, & dont know what the PO did for maintenance. Does anyone know what thread is on the sensor, so I can just swap out with proper gauge adapters, 1st time, without taking apart & chasing parts.

Yes, thread is 1/8" BSPT - British Standard Pipe, tapered thread. NPT will start to thread in but it is different threads per inch and does not fit correctly.

Yes, thread is 1/8" BSPT - British Standard Pipe, tapered thread. NPT will start to thread in but it is different threads per inch and does not fit correctly.

 

Is this an easy to find adapter? I cant recall ever seeing such, but I never looked either.

I know you can get them through Matco. I bought my newest oil pressure gauge through the local Matco distributor and it came with the proper fitting.

I kinda doubt you'll find one in a local hardware store. This seems to be a fairly common thread on Japanese and European cars though so most gauge kits that have adapter fittings included will probably have it.

An adapter to what? 1/8" NPT? Yes, those are very common. McMaster.com sells them. Also even places like Pepboys will have them, though usually you have to buy an assortment which is near the gauges aisle. Grainger and MSC probably carry them too. SummitRacing and Jegs probably have them though might have to get the assortment. What I didn't check was to see if Amazon/SmallParts.com has them, I would think they do.

An adapter to what? 1/8" NPT? Yes, those are very common. McMaster.com sells them. Also even places like Pepboys will have them, though usually you have to buy an assortment which is near the gauges aisle. Grainger and MSC probably carry them too. SummitRacing and Jegs probably have them though might have to get the assortment. What I didn't check was to see if Amazon/SmallParts.com has them, I would think they do.

 

1/8 ntp would not be any problem but I thought it was a 1/8 british thread size? Neither one makes sence on a jap car anyhow!

Well it is metric.

What type of adapter you need depends on what size thread is on the hose for your gauge.

Most gauges I've got are usually 1/8" MPT or 1/4" MPT , But I need the correct thread to screw into Subie block & on other side of adapter, american standard FIP or MPT . Then I can attach my analogue gauge.