So i guess i need some help. My wifes 01' accord ex auto trans with only 1 mod (cold air intake) is giving a code P1381. I scanned it and found its for an intermiant interuption in the CYP sensor. I changed the distributor since its built in and today the code came back.

Im lost. Where do i look next. The code is pretty specific but i guess the fix isnt. Anyone seen this before? Ive seen a number of different thoughts online but was hoping someone could narrow it down. Thanks in advance.

 

May be the alternator diodes. See this thread:

honda-tech.com/showthread.php?t=2813513

I believe many of the 6th gen Accords came with the Delphi alternator which weren't very good, unlike the Denso alternators.

 

If the delphis are no good can i replace it with a denso or does that not work.

Im just tryin ta get as much info as possible. Im already out about $250 for the distributor and i dont wanna start thrownin parts at it left and right. Im sure anyone could understand that. Shes got a JL 12 in the trunk and it seems ta be stable, could it still be the alt if im not seein any power draws on the car.

 

P1381 = CYP sensor intermittent

Yeah, it's specific to that sensor, but that code doesn't say whether it's a bad sensor vs. flaky wiring or plugs in the car's wiring harness. You're supposed to check that out before assuming you need a new distributor.

 

Lol. Yeah so i have already checked the connectors. They look good. I didnt trace the wires all the way back to the ecu yet. I plan on doin that this wknd. So if the wires check out what do u suggest from there?

 

Just thought of anoth pice of info that may help. I did test the cyp sensor before changing the dist. The resistance was suppose to be 800 - 1500 ohms. It checked out at 750.

 

That's pretty close 750 - 800 so I don't know. What about the resistance of the new one? I haven't had one go bad on me, so don't know firsthand whether 750 would be low enough to call it 'failed'.

 

Yeah i thought it was pretty close too. Someone that knows a little more about electrical told me it was too much. So much for that. I need ta check the resistance on the new one. No time till this wknd.

As far as tracing the wires for the distributor, im just looking ta make sure i got a solid connections to the ecu right? A simple continuity check? I cant find a diagram for the ecu harness either.

 

To add to that, if the wiring checks out should i jump to the alternator. Ive read a few threads in different places online were people solved this problem with a new alt. Doesnt make sense to me but i dont know what else it may be. The rest of the spark system only has 25K miles on it. Its not that old for those parts, i dont think anyways.

 

Two checks for the wiring. Continuity back to the ECU, and you also want to verify there's NO continuity to ground.

You can always CHECK your alternator (I wouldn't jump right out & buy one). Does it start & run?
1 - Battery voltage after it's been parked overnight.
2 - Turn on headlights & blower & measure battery voltage (engine not started).
3 - Watch how low the battery voltage gets while starting.
(drive around a bit)
4 - Battery voltage with engine idling after it's been warmed up with lights/etc OFF.
5 - Battery voltage with engine idling; warmed up, every electrical load ON.

Post back with the voltages for those 5 conditions, it might give us something. Best test for bad rectifier bridge is an oscilloscope on the alternator output.