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Hi, I can help.
I'v got some sevice news articles here about that code....
DTC P1381 Set? Check the
Ignition Coil Shield
Troubleshooting a DTC P1381 (CYP sensor
intermittent interruption) in a '98-02 Accord L4 or
'96-00 Civic? If you can't find anything wrong
after following the procedure in the appropriate
S/M, then remove the distributor cap, and make
sure the coil shield is in place and it's correctly
installed as shown. If the coil shield installation
looks OK, then the ignition coil is the probably
faulty and should be replaced.
go to step 2.
right, properly install the coil shield.
2. Unplug the 4P connector from the alternator
3. Test-drive the vehicle.
alternator unplugged, replace the distributor
4. Plug the 4P connector into the alternator, and
use the HDS to do a charging system test. Look
at the alternator diode pattern on the display
replace the alternator. A faulty diode can
cause electrical interference that sets this
So I'm looking for EMI/RFI interference.
The alternator makes an odd noise when the engine first starts but then goes away. Would this have something to do with it? The sound is a quick "Burt" (low pitch, mechanical noise -not a belt squeal) noise.
How should the coil shield be installed?
What would indicate an improper installation of the coil shield?
Are the alternator diodes available from Honda? Perhaps a rebuild kit> If so, what is the part number?
I personally have never repaired this problem before, but the Honda info is always good.
First the coil. It has a metal shield on the back of it. You must remove the coil to see it.
Take the shield off and make sure there are no tracking marks under the shield or anywhere on the coil. I dont think the shield can be installed wrong, it could be missing.
If an alternator makes any noise its usually got an issue starting. yes.
Honda ha reman. alternators, no parts available. Very good units with 3-36 warranty
There is a plastic shield, thats not the one they speak of. Its the metal one of the back of the coil.
I checked the resistance of the ignition coil primary and secondarys. They both seem within the specs I have. There didn't appear to be any signs of arcing but the Anode tip of the coil had a rounded head that appeared to be drooping on an angle. Is the Anode tip supposed to be straight or rounded? I'm not sure if it is melted.
It shouldnt be on an angle, look in the cap and see if there is a spring in the area where the coil fits. cant remember.
Check your engine number I believe you have the top dist. in this pic.
Ok, then the coil is ok.
Look at you charging system then. You can have the alternator tested and see if there is excess doide ripple.
looks like it
Ok, you're welcome