2001 OBW codes P0446 and P1400

[baccaruda]

I'm new to both OBDII and owning cars less than 25 years old and I'd be grateful for some help chasing these two codes down so I can get the CEL light off and get this car sold!

 

The car:

2001 Outback (Legacy) wagon

2.5 / 5MT

"Weapon R" cold air intake (I don't believe that the aftermarket intake could be a factor here but thought I'd mention it.)

 

The codes:

P0446: Evaporative Emission System Vent Control Circuit

P1400: Fuel Tank Pressure Control Solenoid Low Input

 

My problem is that I don't know this car's systems well enough, nor do I have any FSM-type material, to know where to start with these codes. Aside from getting a newer gas cap, I'm not sure what else I would start to check. I've searched and found a bit concerning P0446 but the component names and locations are a bit vague.

 

thanks

[Legacy777]

I'm not sure if you had found any help on this.

 

My first suggestion would be to reset the ECU and clear the codes, and then see if they immediately come back. If they do, then I'd run down the diagnostic checks they have in the manual for those specific codes.

 

Here's the factory manual which does have pretty good step by step diagnostics for each code or DTC.

 

http://www.main.experiencetherave.com/subaru_manual_scans/2000+_Legacy_FSM/

[baccaruda]

Thanks Josh. I have cleared them with a borrowed reader and they return immediately. I grabbed a couple of gas caps from Spalding yesterday in case they help.. thanks for the link.

Edited November 2, 2009 by baccaruda

[Fairtax4me]

One of the evap hoses is probably cracked or chewed through by a mouse or something. All of those components should be at the back of the car near the fuel filler tube. The pressure sensor is inside the car though to protect it from the elements.

[baccaruda]

Thanks.

 

 

Does anyone know which other (earlier) years' components might interchange with the 2001's? I'm going to try to find some replacement sensors at the parts yard and they have some late 90s Outback/Legacy cars there...

 

I want to get my replacement parts in order first so I only have to disassemble and reassemble the stuff in my OBW once..

[baccaruda]

OK... I replaced the drain valve and the fuel tank pressure control solenoid (both used parts from a non-coding car) and it fixed these codes....

 

 

but now they're back!

 

This car lives at my dad's place and spends most of its time sitting, if that's at all relevant. Has half a tank of gas.

I'm hoping that there's something ELSE in common concurrence with these two codes that doesn't involve changing all of the rubber lines under the car... anyone know?

 

thanks,

Andy

[Fairtax4me]

Hmmm... I just noticed these are circuit codes. (must've had a brain fart before) You might want to check the wire harness connector(s) for those two parts and make sure there is no corrosion in them. Sometimes all they need is to be unplugged ans plugged back in a few times. If you find them looking nasty spray them with contact cleaner and load them up with dielectric grease before you plug them back in.

 

If that doesn't help you might want to find out which connectors in the body harness the wiring for those passes through and check those as well.

[baccaruda]

Thanks! I did load up the acutal sensor-to-harness connectors with dielectric grease, and they were in clean condition besides. I'll chase down the other connectors and maybe the ground points for it.

[baccaruda]

OK, the wiring harness connectors looked clean and are now full of fresh dielectric silicone grease. I pulled the panel off of the cargo area interior and the grounding point was clean and tight.

 

I just read Mikevan's Thread of Agony and I have to admit that I can't find my good multimeter and I'm not very experienced with them to boot.

I was hoping that my digital copy of the 2000 FSM would have a vacuum line diagram but alas, it does not. I'm wondering if the Drain Valve and Fuel Tank Pressure Control Solenoid share a particular vacuum line or something that might be cracked.

 

I also might "borrow" an ECU from the wrecking yard and throw it in this weekend...

[Cougar]

The P0446 error code refers to the evaporative emission purge valve so don't confuse it with the fuel pressure relief valve.

 

Check the yel/red wire on the purge vavle and make sure 12 volts is getting to that point. Next check the power on the wht/blue wire of the solenoid and then see if the voltage is the same on pin A2 of the ECU. If it isn't then check the connection of B22 pin 2 and make sure it it is making good connection.

[baccaruda]

Thanks for the reply..

Regarding the P0446, I am targeting the "drain valve" by the charcoal canister. "Drain Valve" is what it's called st EN(H4)-202 in the FSM PDF set that Josh linked. I wish I had simply targeted the wrong part, though.

[Fairtax4me]

The P0446 error code refers to the evaporative emission purge valve so don't confuse it with the fuel pressure relief valve.

 

Check the yel/red wire on the purge vavle and make sure 12 volts is getting to that point. Next check the power on the wht/blue wire of the solenoid and then see if the voltage is the same on pin A2 of the ECU. If it isn't then check the connection of B22 pin 2 and make sure it it is making good connection.

 

The drain valve and purge control valve are two different valves. The purge control valve is hidden under the passenger intake runners. Drain valve is the one by the charcoal canister.

[baccaruda]

Well, the "bad news" is that the salvage yard ECM threw the same two codes.. the good news is that I can return it and get my $100 back and that I found my multimeter, and that it's not supposed to rain Saturday...

 

This car has an aftermarket tube/cone air intake under the hood; it appears that there aren't any loose vacuum sources or anything near it.. am I safe in assuming it doesn't affect this problem because the components involved in the codes are fuel-tank-related and at the back of the car?

[Fairtax4me]

I don't think the intake has anything to do with this. Have you had the chance to check power on the two connectors Cougar mentioned?

[baccaruda]

Not really. i just found my better multimeter which should make that part of the troubleshooting a lot more feasible. I'll be taking advantage of a clear forecast this Saturday to go through all of the diag stuff in the FSM.

[baccaruda]

The multimeter read both components as below the acceptable voltage parameters... so I replaced them with new ones from the dealership... and they are still coding

But this time, although the check engine light comes on each time I clear the codes and start the car, it only throws the P1400 and P0446 codes every few times after I run the engine a little.

I don't know how the car can trigger the CEL without codes, but noticing that running the engine a little is what seems to get the codes to pop makes me wonder if there's a vacuum issue somewhere under the car.. if it's been that way long enough, could the old sensors I changed out have gone bad, burned out, from being in a trouble state for a long time?

 

I've been through the .pdf collection several times and it appears there is no map or diagram of the vacuum lines in general. Does anyone know of such a diagram?

[idosubaru]

if it's been that way long enough, could the old sensors I changed out have gone bad, burned out, from being in a trouble state for a long time?

no, but im' not sure what/why you're asking. i don't think "being in a trouble state" comes into play here.

 

so you were supposed to measure voltages? was that with the car running? how did you measure and what did you get?

 

I've been through the .pdf collection several times and it appears there is no map or diagram of the vacuum lines in general. Does anyone know of such a diagram?

doesn't have it printed underneath the engine hood does it? some older subaru's used to have vacuum diagrams under the hood, like XT6's. never needed one or looked at newer stuff?

[baccaruda]

Hi Gary.

There is something under the hood.. I'll have to look at it. I can check a friend's car tomorrow at work to see if it's likely to be useful. Thanks.

 

 

 

"CHECK DRAIN VALVE.

Measure resistance between drain valve terminals.

 

Is the resistance between

10 and 100 Ω?"

 

Resistance was less than 1. My multimeter was set to "20," one setting counterclockwise to the MM pictured. The readout gave a fractional amount less than 1 for both parts, the FTPCSV and the drain valve. I put new ones in the car today and it still codes, but intermittently.. the CEL still pops every time though.

 

Edited June 8, 2010 by baccaruda

[idosubaru]

oh okay, you said "voltage earlier" so i was confused what you were measure, but you meant resistance.

 

did you compare the resistance of the new ones to the old ones?

 

did this car ever have a hitch on it? when i installed mine i remember that box and hoses all up in the rear crevices of the passenger side rear corner. is that where this emissions stuff is you're messing with? i feel like it needed to be slightly moved or pushed aside while installing the hitch bolts. just a wild guess, maybe someone didn't hook it up right or cracked something, etc?

[Cougar]

Just a note about the picture of the meter shown above. The meter is set to read temperature, not voltage. If you are trying to measure a low resistance then the dial should be set to the 200 position in the Ohms section. This would put the dial indicator in the 6 o'clock position if it were an hour hand.

 

Whenever you measure resistance there should be no power to the device under test and have at least one lead isolated from the circuit to prevent a alternate path that could cause a wrong reading from the meter.

Edited June 8, 2010 by Cougar