My 98 Subaru Legacy gt is having problems with the evap sensor being ready so I can take my emissions test. I've been doing drive cycles for over a month now. I replaced the battery and gas cap a couple weeks back and did more drive cycles. I then brought my car into a shop for an engine diagnostics test, which came back saying nothing is wrong. They then spent 2 days getting my evap monitor ready, which they said they did after hours of work. I picked my car up and went straight to deq, of course the evap sensor wasn't ready. I'm very frustrated. Any ideas of what is going on or what I can do? Thank you

That's the hardest monitor to get set to ready. There's many conditions that have to met for the ECU to run the test, like fuel level in a certain range, temperature in a certain range, throttle position etc. There is a bulletin from Subaru somewhere with details on how to get it set. So I take it you have to get all the monitors set to pass in your area? Fortunately in my area in NY they allow up to two monitors to be not ready on soobs of that era, after ~2000 only one can be not ready.

Edited January 16, 201610 yr by porcupine73

Done it for CA emissions a number of times. Fill the gas tank to between 1/2 and 3/4, get the engine up to operating temp, drive 55mph over as flat a surface as possible for 3-10 miles at a time. Cruise control is your friend. Usually takes about a half hour of such driving to get that monitor up. Sometimes longer. For some reason, the cars with manual transmissions take longer than the automatic.

Yeah I have a manual. I have had my gas at 1/2 tank to 3/4 and repeatedly done the drive cycle. If my monitor was ready like the mechanic said, shouldn't it stay ready as long as I don't disconnect the battery?

Does it have the original ECU? If it was replaced with a '96 or possibly '95 ECU for some reason then those may reset all the monitors every time the engine is shut off. If you have or can borrow a scanner, or have a smartphone I believe there is some inexpensive gadget and app you can get that basically makes the phone work as a code scanner. if that will show the monitor states then you can check for yourself when it is set to ready, verify that it stays at ready when restarted, check it right before you give it to deq, etc.

I've chatted with the smog shop I use here and they happen to be right next to a Subaru garage, so they see a lot of them. They said they've seen some weird ones where the car will reset the monitors every time the car is turned off.

 

Here's my advice - buy a cheap OBDII scanner. There's one for $15. on ebay and harbor freight has a little nicer one for around $45. (Coupons for $20% off a single item can be found in a google search) Drive your car through the cycles again and check the monitors yourself. Once you get them to the ready, take the car in for smog without turning it off. There may be an underlying glitch somewhere resetting the monitors, but this would be the most reliable way to get through smog.

IIRC the 98 ECU has different pinout that 97-96, so an ECU swap with an earlier model year isn't likely.

 

95 and 96 reset the evap, catalyst and EGR monitors every time the key is cycled, and the EPA actually issued an exemption on those model years because of that.

 

But 98 should be keeping those monitors in a ready state after turning the key off and back on.

 

If it's not maintaining the ready status, there could be a power issue to the ECU, such that it isn't keeping its memory powered in certain areas. Or there could be an internal problem in the ECU.

 

Have you been following the Subaru TSB to set the monitors? http://www.ultimatesubaru.org/forum/topic/134825-subaru-tsb-how-to-set-your-im-monitors-for-emissions-testing/

Edited January 16, 201610 yr by Fairtax4me

It has the original ecu. I guess I'm going to buy an obdii scanner and drive and hope to get the evap in a ready state. I'm still puzzled why it was ready and now isn't. Hopefully I don't need a new ecu. I live in Oregon where are monitors murat be ready.

So I borrowed a obdii scanner and drove for a while today. Eventually I got a p0440 code, followed by my check engine light coming on. I know it's a evap system malfunction at this point, at least this might help me solve the problem. It's weird that it took this long for an error code. Any advice?

Check your sensors and the small hose routing on the passenger side. An open end, a cracked line or a bad sensor can cause this. Check the Evap hose routing and canister. Common issues resulting in that code is a failed gas cap or filler tube (especially if rusty)

Yes also if it has EGR check the little metal lines that run from that near the throttle body. There's a bulletin out about those possibly rusting and getting plugged and causing problems. Also near the passenger fender where the pressure sources switching solenoid and stuff is there is a small white filter, that sometimes gets plugged too.

So the problem has been identified. So the purge solenoid canister at some point malfunctioned, so a previous owner, possibly mechanic decided to take off the hose and stick a screw into it rather than replacing it. I still can't believe it, hopefully this information helps someone out but this seems pretty unlikely anybody would do this to they're car. Anyways thank you everyone for your help and advice.

Still curious to me that it would throw a code. Standard procedure when swapping a 95 or 96 2.2 into a 2.5 car is to simply cap the lines. Unless one was plugged and the other was open. I've passed two of them through CA smog with lines run back on themselves and never a check engine light. A 15+ year old canister wont really be functional anymore.

It took a really long time before a check engine light came on. So you got your evap monitor to "ready" status with plugged lines?

It took a really long time before a check engine light came on. So you got your evap monitor to "ready" status with plugged lines?

It might be one of the codes where it only illuminates the CEL/MIL after something like 3 successive failed tests. Before that you might be able to read the code as 'pending'. (Of course it won't go to ready until it passes the test, which yes, with plugged lines would probably never pass since it won't see the proper pressure changes in the fuel tank vapor space).