Firstoff great forum, and great help. My first post here Over the past few datys, I have been reading the posts here lot of helpful information from knowledgable contributors. Thank you.

After making several trips to the shop for a P1456 over the years.....seems to popup every year around the registration time , I've decided to tackle this myself.

I spent some time reading posts watching videos to understand EVAP system and the general purpose. I'm still not an expert on the subject but I have fair bit of understanding on the subject. I took a trip under the car to see where the various components were and was able to locate most of the valves and solenoids of interest.

I am ready to get my hands dirty but I'm looking for list of things I'd need....
I have a multimeter,
I'm planning to get this hand vaccum pump. I'm open to suggestions on this one $30-50 range. https://www.harborfreight.com/mityva...ump-39522.html
I keep reading up HDS to activate/inactivate valves using handheld meters
or laptops and such. This is where I'm completely lost. Searching on web brings up cables starting at $20 to tablets/laptops upto few grand. Do I need of these to do this test? If you can point me to a post or educate me a bit on what the capabilties are of each of these and what I can get without breaking bank

What else do I need? smoke machine?

Thank you very much for your help.


Update.....
After doing a bit more searching here...found the service manual for my car which helped answer some of my earlier questions.... seems like what the HDS would have done easily can be done (atleast for this procedure) at the ECU using a jumper/wire.
I'll start with the steps listed and get additional equipment as needed.

One more Q
Which one is good OBDII scanner for Honda's? any generic one off of amazon works? wired/bluetooth (with phone app)....Or this a matter of preference?

 

See attached. This should help. Check South Main Auto channel on youtube for help. A test light is very useful to verify grounds, voltage availability, etc.

A harbor freight vacuum pump should work fine for DIY.

good luck

 

Be very cautious jumping 12V and ground directly to the ECU. If you need to open/shut a valve, you may want to apply 12V and ground directly to the unplugged valve you are trying to activate/deactivate.

 

I believe it can be done with a cheap HF multimeter (VOM) a mityvac, and some jumper wires.

Someone on here posted up a really good go thru, but I think it was for a P1457 code, but he also ran the P1456 code sequence as well since he had both coming up. I think it took him about 2 weeks before he finally got it to stop coughing up a code, as he replaced both the valves and the switch for 1 of the valves (working off the trouble shooting guide in the FSM). At 1 point he thought he was going to have to replace the ECU, but ended finding a broken wire under the sill plate going to the "shut valve".

Maybe 1 of the old timers on here might remember who it was.

 

https://www.hondaaccordforum.com/for...-1999-a-27179/

All the valves in the EVAP system have (+) wire hot all the time with 12v battery voltage. The ground-side wire is grounded by the PCM when it wants to operate the valve. This seems like the "traditional" method for Honda.

So a DIY guy doesn't need the expensive HDS. (The HDS is quicker because you can command stuff to open or close without making jumper wires)

Unplug the valve that you are checking. Make up jumper wires for (+)12v and ground, maybe using alligator clips or something. Use the (+) battery post and any convenient good metal ground.

Before you even set up the vacuum or whatever, just touch your jumpers to the valve's electrical plug. When mine threw an EVAP code, one of the valves didn't even make any clicking sound - it was rusted into a nonworking lump. I took a chance & replaced that one, hoping it was the only thing wrong with the system. I won the bet and the code didn't come back.

Now some of the EVAP functions are more complicated to test properly, with vacuum & whatever. But if you find a rusted lump of a valve, go ahead and replace it. The thing about the HDS tester is a pro who does this for a living can run through all the other tests so he doesn't have to give the car back to the customer saying "lets see if this works...?"

 

Thank you all for the answers, instruction sheet, tips and explanation.

Dropped HDS idea, got the Vaccum pump, test light, multimeter, jumper cables......now the check engine light is gone even before I did anything

At times when the light was on, I definitely could smell gas after a ride. Now the smell is gone and the light is gone.

So, is it gone for good?(meaning did the code get cleared on the computer) OR did it turn off temporarily to do another test and is just around the corner?

any recommendations on a decent OBDII scanner that can also clear codes for situations like these? Any experience with this?

Thanks again.

 

For a 1998 Accord you can clear the codes by pulling fuse #13 in the right-side interior fusebox (end of the dashboard near the passenger door hinges).

The whole EVAP test stuff is trying to measure whether your fuel tank & associated hoses & stuff is airtight like it should be. So maybe while you were messing around with it, you pushed a vacuum hose back onto its nipple or something silly like that? More likely the code will come back...?