Hello everyone, I have had the P1457 code for a good while and recently started to look into it.
2000 Civic si (Canada) D16Y8 M/T EJ8
I followed the service manuals instructions on diagnosing the issue, and ended up with "Replace Canister Vent Valve" because the CSV did not shift or hold vacuum when i turned the ignition to on, and grounded PCM terminal A4. (Evap Control Canister Vent Valve) Should grounding this terminal cause the valve to shut? I applied 12v to the solenoid and it shifted and sealed fine so im having a hard time believing there is something wrong with it. I checked continuity from terminals A4 and B2 (PG1) to the 2P connector at the CSV and there seems to be no shorts, and there is 12v present between A4 and B2 when the 2P connector is attached to the CSV and the ignition "ON" I dont really wish to buy a new CSV if my problems are elsewhere.
So i guess im wondering if all this is right? Should grounding said terminal cause the valve to shut? What other things might be wrong? Thanks in advance.

 

Check wire colors to make sure the proper plug is on the solenoid. The 2-wire sensor connectors under the hood are all mechanically the same, they can be plugged onto the wrong part.

Disconnect battery.
Unplug ECU. Leave solenoid and everything else plugged in.
Measure the solenoid coil resistance at the ECU plug.

This confirms that the circuit through the harness and solenoid plug is OK.

 

Here is some information i collected this morning. I hope maybe this will help:
11.4v from the black wire at the 2P to body ground
9.9v from the black wire to the green wire at the 2P with terminal A4 grounded
11.3v from B2 to A4 with solenoid plugged into the 2P
26.5Ω across solenoid contacts
32Ω from B2 to A4 with the solenoid plugged into the 2P
5.7Ω from the black wire at the 2P to body ground?

Also, ive tried attaching a different CSV the 2P and grounded terminal A4, no luck.