try parts.subaru.com or 1stsubaruparts.com ?

 

@davidtraxler

The P0028 is related to the bank 2 VVL system, and could be caused by a faulty VVL oil pressure switch or oil switching solenoid. However, according to the FSM, the external VVL-related parts are at the back of the H6 heads (both sides) and the VVL oil pressure diagnosis switch has a single terminal connector.

What area of the engine is in the photo? There appears to be a radiator hose fitting (lower left), which might put the circled part at the front of the engine, but I'm not certain that's what it is. (Perhaps a photo from further back could better identify the location, and thereby the circled part.)

Edit: Disregard. I think I found it in this post, right hand photo, to the right (as viewed) of the AC Compressor and more-or-less behind the oil dipstick. Now to find it in the on line parts catalogs . . .

 

I’ve had a look here and I can’t identify the part.

Now I’m concerned I’ve checked the wrong solenoid. As it looks like there is part 10921 on the front of the engine. But also 10921a/b at the back!


https://parts.subaru.com/p/Subaru_2...005_Outback-Limited-30L-5AT/VALVE-ASSEMBLY-OIL-CONTROL/49223107/10921AA040.html

 

That’s correct, the photo is the front left of the engine. The circled part in question is underneath the manifold protection frame.

 

The circled part in the photo is the engine coolant temperature sensor. The solenoid to the right (in the photo) appears to be the Bank 2 (LH) intake camshaft oil control (i.e., VVT).

Looks as if there might be a leak (oil or coolant?) in that area, but that's separate from the parts that are related to the VVL code.

 

Aha! So the coolent switch might need replaced as well(could be leaking) but it isn’t throwing the code!

So P0028/26 refers to the VVL, and I inspected the VVT solenoid!

Back out to the car then.

Thanks!

 

It's the coolant temperature (ECT) sensor (i.e., not a switch). Is that oil or coolant around the sensor? If oil, then it's from something else. It looks as if whatever is around the base of the sensor is also higher up near the solenoid, so it could be oil that's run down to the ECT sensor.

Keep us informed . . .

Attached shows location of LH VVL components. Arrow points to the oil pressure diagnosis switch, the VVL solenoid is to the right (in the diagram), and the oil temperature sensor is below the switch.

 

Just got back in. What an absolute PITA to get to. Had to remove... some kind of vacuum pump to get to it.

I’m not sure how I’m going to get a deep well socket over the oil switch in the cramped space.

I took out the solenoid while I was in there and it looked fine from a visual inspection.

Another day to continue the investigation. Thanks again!

 

RE: the pressure switch, be very careful when installing. The base has a pipe thread configuration, so it applies increasing pressure on the thread interface as it's tightened. Too much tightening can crack the mount area on the block -- there's a number of cases here-- and that could be a really big problem.

Is there any sign of oil in the oil pressure switch connector (if you were able to get that far), or around the base?

Do you have a digital multimeter and can reach the single contact in the switch connector? Sometimes, a bad internal switch contact can cause the P0028. (https://www.subaruoutback.org/forum...blems-maintenance/49468-variable-valve-lift-oil-pressure-switch-resistance.html). This test might confirm whether or not this is a problem with yours. (I'd probably compare the left side and right side switches as well.)

 

I ment to post this yesterday and didnt hit post, sounds like you got further along. I would have checked the resistance of both sensors first. You have one oil sensor for each VVL solenoid. Check the resistance to ground for both, if they match, from memory I think they a good one is about 16 ohms, they are both almost certainly ok. If one on your bank with the code is reading zero, replace. If they are both ok, replace the VVL for that bank.

 

I ment to post this yesterday and didnt hit post, sounds like you got further along. I would have checked the resistance of both sensors first. You have one oil sensor for each VVL solenoid. Check the resistance to ground for both, if they match, from memory I think they a good one is about 16 ohms, they are both almost certainly ok. If one on your bank with the code is reading zero, replace. If they are both ok, replace the VVL for that bank.

Indeed, checking/comparing the VVL oil pressure switch resistances is a good idea before anything else.

However, when the engine is off, the pressure switches should be "closed", and the resistance between the switch connector terminal and ground (engine block or battery negative post) should be low; ideally a closed switch would read zero Ohms, but practically, taking into account test meter lead resistance and test probe contact resistance, an indication of a few Ohms is likely. (The linked thread has examples.)

 

Right. I’ve whipped out the multimeter and read up on the instructions. I’ve got no idea what I’m doing.

I’m mechanically minded but this thing is beyond me.

I used the correct posts and I had the black lead on the negative battery terminal and the red less down in the switch trying to hit the metal pin, and the ohm thing stayed at 1. Never moved.

Engine off.

It looks impossible to get to the back one switch without some serious removal of impediments, so I want to be sure I’m testing it right...

What should the multimeter be set to?

I did notice when I pulled off the wire on the switch it didn’t have a clip that needed depressed, it just came off. When I re-attached it clipped back in.

I reset the codes and went for a little drive and... as they say in the movies... the vtec kicked in.

I’ll keep you updated. Thanks again all.

 

Right. I’ve whipped out the multimeter and read up on the instructions. I’ve got no idea what I’m doing.

I’m mechanically minded but this thing is beyond me.

I hear you. I can turn it with a wrench, or hit it with a hammer. I can even solder it, if you tell me what's-what. But I am still a caveman.

 

Well the CEL came back on. Haven’t checked the code yet, but safe bet it’s the same.

Will try to whip out the multimeter tomorrow after the engine has cooled and follow your advice and see if I can get a reading on the switch.

Step at a time.

 

Did the meter respond as expected to

Black (negative) lead to battery negative terminal or another good ground point. Then, touch the red (positive) lead to the engine block in the vicinity of the oil pressure switch. The meter indication should go from "1" to a low value, perhaps less than 1.0 Ohms.

Also, are you able to get to the VVL oil pressure switch on the other side to compare?

Both are just to make sure the meter and measurement technique are good and that the absence of any change when testing the left side switch is definitely indicating a faulty switch. The meter is similar to several I have and quite adequate.

 

Meter didn't budge off of '1' no mater how many different things I touched

I've ordered the correct oil switch anyway as the part was only £12, so taking a chance.

 

Meter didn't budge off of '1' no mater how many different things I touched

That's odd. If the tips of the test leads are touched together, the reading should go to zero. Similarly, if one test lead tip is at the battery negative post or to a good ground, and the other is in contact with the engine block in the vicinity of the VVL switch the meter again should change from the "1" indication (as in the photo) to zero. If it doesn't in the first case, then there's a fault with the meter. If it doesn't in the second case but works in the first, it's likely just a bad contact between the test lead tip and whatever it's meant to make contact with, in which case some cleaning/scraping of the surfaces should work.

I've ordered the correct oil switch anyway as the part was only £12, so taking a chance.

Didn't realize you're not in North America. (Some difference are possible.)

Let us know how it turns out.

 

If the senors are reading the same, I would replace the VVL solenoid on the bank that is throwing the code. Its about $100 US from an online dealer

 

Update: just swapped out the bank 2 sensor with the new one. The new sensor was reading like 0.05 or something or 0.5 not sure, still not a master of this multimeter.

The old sensor doesn’t cause the multimeter to move off of 1. Rubbing the two pins together gets a reading of like 0.03, so I’m assuming something is wrong with the switch I pulled out.

I’ve reset the CEL and I’ll go for a drive tonight, however it’s taken 20-30miles for it to come back on previously.

Fingers crossed.

 

300 miles later and we are in the clear. Thanks for your help everyone!