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Discussion Starter · #1 ·
I'm down to one code: PO130, front O2 sensor.
I just replaced it with an OEM so I don't suspect it's the sensor. This weekend I will check the connections.

I did have some moisture in my relay box under the hood earlier which I cleaned up. Is there a fuse or relay that controls the front O2 sensor? Also how do you actually test a relay compared to a fuse where it's either good or bad?
Also, I have a diagram of the relays calling several of them "SPF". Can anyone list which one actually controls what?

One more question, can I replace these cheaply thru Advance Auto or are they a dealer item.

Thanx in advance, this board has kept my Subie running!
 

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'97 Outback Limited, 2.5 DOHC, Automatic, ABS
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P0130 is the sensor part, not the heater which would be p0135. No fuse or relay for your code. You will need to scan the data from the computer to see what's going on. If you don't have a scanner, easier said than done is you get your DMM, set it to dc volts, and "backprobe" the sensor. You'll need the wiring diagram of the sensor, or if you are lucky, the new sensor has a black, white, gray or blue wire. (Should be three wires)Black is ground, white is heater, other is signal. (4 wire sensors have 2 white, black, and gray or blue, the white is always heater) You'll need some 1" safety pins. Slide the pin into the connector from the engine harness side, thru the rubber seal along the wire until you feel it hit the back of the pin in the connector. Do not poke a hole in the wire! On a cold start, I mean cold, the meter on black and white should be around 12 volts. Got 12 volts? You should have 12V as there is no P0135. Fuse/relay are good. No volts, ground the DMM to the block, got volts now? The ground wire is bad between the sensor and computer. Do not put a 12V test light to this wire as it grounds to the computer and you may kill your brain. Do not run a new ground. Good ground? Take the pos lead of the meter and connect to the signal wire. At a cold or warmish start you should see about .45V, as the engine warms up, in about 60-90 seconds this should be changing up and down, about .10V to .90V. This is a healthy sensor. A weak sensor goes .4V to .6 volts. This is what almost always sets a sensor circuit code. It is also very possible that the sensor you bought is junk right out of the box. For anyone else reading this, good aftermarket brands are Standard Ignition, NTK, Bosch, Nippondenso. Avoid Borg Warner. Codes set with a certain priority, always chase the lowest number code first. What sets a sensor code is that the computer didn't see the sensor change from that .45V cold start voltage after the engine warmed up. A very lean (think vacuum leak) or very rich (fuel pressure regulator blown out and dumping fuel thru the vacuum line) might cause this code, which would stop the computer from setting a P0171 lean or p0174 rich code. Yes it's confusing....but hope this helps, S
 

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Discussion Starter · #3 ·
That absolutely helps and is crystal clear. Thanx so much for the write up. I'll be on it this weekend and let ya know how it turned out.
 

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Discussion Starter · #4 ·
It was an easy diagnosis and repair. The ground wire was completely severed about 3/8" above the connector on the car side. i.e. not the replaceable sensor side. Soldering iron, liquid tape and electrical tape got the job done.

Thanx for the knowledge Stella501!
 

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'00 Outback Limited Sedan 2.5l Auto, Black, '98 Kawi KLX351R, '99 HD XL1200Sport, '08 Suzuki VStrom
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****! That was an awesome write up and quick resolve of what could have been a major headache! Way to go Stella501!

Does anyone around here use the Feedback?!?! Oh, now I see its only setup for selling/trading on this forum! Thats too bad, Stella501 deserves a kudos for the excellent help!
 

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Discussion Starter · #6 ·
I would agree wholeheartedly Sub-Goon! For the first time I actually understand my front O2 sensor.

I really do love this forum. I bought my 99 OBW as a mechanics special and this forum has helped me to put it into top shape. I'd have been screwed without it.
 

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'97 Outback Limited, 2.5 DOHC, Automatic, ABS
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This came up at work this week. Check to make sure that the wires to the front O2 are secured in the bendy thing, or it will get chewed by the axle. S.
 

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Discussion Starter · #8 ·
Yes sir, I even went so far as to ziptie it to the steel power steering hose to keep it away from the axle.
I passed emissions on Friday! I ended up replacing both O2 sensors and still got a code, so I pulled the exhaust out and replaced the gasket between the cats and everything cleared up. Thanx again for all the help!
 

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'97 Outback Limited, 2.5 DOHC, Automatic, ABS
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Cool, and I have to hang my head in shame, forgot to mention that the tiniest leak anywhere ahead of the downstream O2 will cause all sorts of havoc.
 

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testing 02 relay/fuse

i'm not quit sure with this test. is the connector apart for this test. it sound like it was apart to test for 12volt on the engine side of connector, but the signal test, the post goes to sensor gray/blue terminal and the connect is apart?
 

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Great forum guys!

I have a 1995 Subaru Legacy Wagon auto transmission, 264,000 miles when the speedo broke 6 months ago. It has lots of problems (can’t go in reverse for one! lol) but the one I'm facing now is almost exactly as mentioned above -
Car always started no problem, although it had had some hesitations after it stood out in heavy rain.
Few weeks ago it sat out in said heavy rain and hesitated to start next morning, but finally got going. Stopped at a gas station on way home, and couldn't start it after that. Left it at the station for 5 hours and came back and it finally started after a good few tries. Drove it straight home, disconnected the battery and went away for two weeks on work job.
Came back, hooked up the battery, she cranks over fine but no start at all.
Sprayed starter fluid into the air intake and cranked her, she started right up and then died.
Removed the fuel filter, then turned ignition key, no fuel coming through.
TRIED to test the power to the fuel pump, removed the fuel pump cover plate and disconnected the *********** supply connector, but could not detect any power (honestly not sure if I did that right - placed a power probe on the line side socket of the white connector, probe side into the blue line w yellow stripe socket and other end alligator clip connected to a paperclip inserted into the black socked immediately below the blue & yellow one; also tried with power probe into the blue & yellow socket and alligator clip to a ground in the trunk; either way, no power detected.)
Looked for and found three grounding points in the engine compartment, one next to battery and two others on each side of the engine compartment close to the windshield; removed all those bolts and connectors, sanded & wire brushed all connectors and bolts and put all back in place. That didn’t fix the fuel flow issue but at least now my radio antenna doesn’t go up & down on it’s own accord even when the radio is turned off lol
Found the location of the Fuel Relay switch (thought I’d check that next) but it’s way up under the dash on far left side, above a bunch of wiring and impossible for me to get to without taking out a ton of wiring brackets etc which I’m not comfortable with doing without screwing something up.

QUESTION:
Could it be the O2 sensor/s that’s causing all this, and not the fuel relay switch?
If so, any guidance on where I could find the O2 sensor/s? (Some folks talk about one sensor, AutoZone diagrams show two or three??)

If it could be the Fuel Relay switch, any suggestions on how to get to that darn thing??

Any help appreciated, trying to keep my baby going, she’s been in the fam since day one.

PS: Other “features” just FYI, but I don’t expect answers to any of these, as all I want to do is get mobile again! :
Won’t go in reverse (has at time not gone into gear at al, but for now seems to go in forward gears OK; tranny was flushed and ‘treated’ with magic sauce by local guru, that did nothing).
Speedo stopped working about 8 months ago, same time as I was having some problems with the transmission not going into gear or sticking in 1st gear. Got tranny working again just by keeping trying, but speedo never came back to life.
Drivers window won’t go up or down, but motor can be heard running when switch is pushed.
 

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'98 Outback
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Is the check engine light lit? Steady or flashing? If so, get the codes read.

If no CEL, it's probably not a sensor problem.

Next logical step is checking/replacing the relay.

If you're comfortable with it, you can try jumpering 12V to the fuel pump to make sure it works.

Speedo input is a vehicle speed sensor, but you'd have a CEL for that.
 

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TRIED to test the power to the fuel pump, removed the fuel pump cover plate and disconnected the *********** supply connector, but could not detect any power (honestly not sure if I did that right - placed a power probe on the line side socket of the white connector, probe side into the blue line w yellow stripe socket and other end alligator clip connected to a paperclip inserted into the black socked immediately below the blue & yellow one; also tried with power probe into the blue & yellow socket and alligator clip to a group in the trunk; either way, no power detected.)
What type of "power probe" are you using? Is it designed to work with 12 V DC? Does it work properly when connected to a known good source of power (e.g. across the battery)? Just want to be sure the test equipment is right for the job . . .

The fuel pump relay activating coil is powered from a fuse in the cabin fuse box. This same fuse powers the ignition coil. The ignition coil, which should be fairly accessible, has a three wire connector. The yellow wire at that connector should have battery power on it when the ignition is at On. Check for power there; this will confirm the supply from the fuse.
 

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Thanks for the prompt reply guys, much appreciated.
- Check engine light has been on for months, steady. Whatever caused the CEL to come on, didn't seem to effect the functionality of the car other than what I know doesn't work already, so I've just ignored it TBO. I can't find anyone locally who has the pre-1996 exclusive Subaru code reader to check the codes, other than the dealer who I can't afford to go to.

Yes I tried to put 12v to the pump with it still in the vehicle via the white connector socket, but it's not easy to do, very little space in that white socket, and if I did get it right I got no response from the pump.
My next plan today or tomorrow was to remove the fuel pump and check it with a 12v connector directly to the pump leads, to see if it turns or not; that way at least I eliminate one item, but I understand from others that the fuel relay could also have blown if the pump is dead.

Yes, the power probe is a small screwdriver type that lights up with power, and yes I tested it across the battery and it works fine. (Similar to photo attached)

"The fuel pump relay activating coil is powered from a fuse in the cabin fuse box. This same fuse powers the ignition coil. The ignition coil, which should be fairly accessible, has a three wire connector. The yellow wire at that connector should have battery power on it when the ignition is at On. Check for power there; this will confirm the supply from the fuse." -
I did remove each and every fuse from both fuse boxes, in engine compartment and under the dash, and looked at each one, could find no breaks visually. (Did not test them with a ohmmeter, but I do have one.) I have no clue where the ignition coil is, but I guess I could look for it. Bear in mind that the car does fire up as soon as you put fuel to it (via the starter fluid in my case).

Appreciate the feedback & help.
 

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Bear in mind that the car does fire up as soon as you put fuel to it (via the starter fluid in my case).
Right, so the ignition coil is being powered, which means the fuse is good.

Rare for the fuel pump relay to go bad, but that doesn't mean it can't happen.

I've attached a wiring diagram page (annotated, highlighted) that includes the fuel pump relay and the fuel pump motor.

Not sure about the 1995 generation, but with later years, when the ignition switch is turned to ON, but not to Start, the fuel pump runs for about two seconds then is turned off. Similarly, when the ignition switch is at Start and the engine is being cranked, the fuel pump should be running.

In the first case there would be battery power at the fuel pump connector terminals/wires (the blue with yellow stripe, to ground, which is usually the black wires) for just the two seconds or so "prime", but continuous with the switch at Start. If you're not getting any power to the harness connector at the pump in either case, then the problem is indeed upstream. Could be the relay, or, a bad connection somewhere in the wiring.
 

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Thanks again, great info.
I agree, and yes I've researched the 1995 model and as per other YTube videos it also has the power to the fuel pump come on for two seconds when key is first turned but before cranking, and I see NO evidence of any power getting to the fuel pump connector when I do that with the power probe connected as you described.

I'm going to remove the fuel pump tomorrow and check it, that should be simple enough.

My challenge is going to be -
a) If the fuel pump is good, then we know it's something upstream, may be the relay or wiring, and how do I find THAT problem?
b) If the fuel pump is dead, then I guess it could be a combination problem of the fuel pump plus some other reason for the lack of power to the pump? And should I be sure that I can fix that upstream issue first, before shelling out for a new pump?
c) Regardless f the pump condition, it looks like I'll need to check the Fuel Pump Relay, and how the &^%$#!! heck does one get to that beast, above & behind all that wiring and connectors?

Any further help appreciated, otherwise I'l report back here after I've removed and checked the fuel pump tomorrow.

Thanks!
 

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The CEL is trying to tell you something, perhaps something very important. Don't ignore it. A generic code reader will tell you most of what you need to know for this car. I got mine for $15 and it's worked fine for my older cars. Some auto parts stores will scan for free.
 

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Wow that's interesting, I was told by both my local mechanic and the local Auto Zone that their reader won't see anything if it's 1995 or older. Maybe I should try them again.
Anyway right now I can't get the vehicle out of my driveway, so getting to AutoZone will have to be after I get it mobile again, but thanks for the info.
 

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If you're definitely not getting any power to the #1 (LY) and #4 (B) terminals of the fuel pump harness connector, then that should be enough to conclude that's a problem that needs to be resolved, whether or not the pump motor works. I'd probably deal with that before buying a replacement pump; the replacement won't work as well if there's no power to it.

As for the question of power, there's several possibilities.

There's no power from SBF-2 (although this is somewhat unlikely).

There is power from SBF-2 to the relay (terminal 2 of the relay connector), but either the relay's switching contacts aren't making a good connection through to terminal 4, or, the energizing coil isn't activating the contacts. In the latter case, this could be due to a bad relay coil, or absence of "turn on" signal from the ECM.

Might be a challenge to narrow down the problem area without some disassembly, but I will try to see what can be done, and perhaps others monitoring this will do so as well.

One thing that can be done easily is to make sure the connection from pump connector terminal 4 (black wire) in fact is a good connection to ground. Use the multimeter to measure the resistance between the connector and a good body ground point. It should be zero, but the meter might indicate some resistance due to the test leads.

edit: FSM suggests the 1995 should be OBD II; common generic code readers should work. Autozone and others might also lend out code readers, requiring just a refundable deposit. Might be worth calling around . . .
 

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Great info and suggestions thanks, I will see what I can do and report back.
Very grateful for the support from this forum.
 
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