2000 Honda Accord LX F23A1 manual 390k miles.

A few months back while I was doing my head gasket job, I broke the knock sensor. I ordered the cheapest one on rock auto and put it back together. I got the code P0325, and drove it like that until I could order another and get the time to replace it. Finally I had the time so I did the job the last 2 days and just finished, took it for a test drive, and the same code showed again. It took a couple days to do the job and during that time I had the battery wires connected to each other to clear codes, which it did (service engine light went off at least). I tested the wire while I was in there with a multi meter, no shorts or opens, I have no way to test shielding integrity or anything like that. I really doubt I was sent 2 out of box failures from 2 different manufacturers.

Anyone have any idea what could be going on? Where do I go from here?

Footnote- it drove like crap before I installed the second knock sensor, it does drive considerably better now.

Thanks

 

For clarity, after you clear the DTC cache and run the engine the code reappears within a minute of driving the Accord?

There aren't any downstream components that could cause a P0325. The knock sensor connects directly to the ECM. That limits t-shooting to the doodad itself, the wiring, and the connector(s). That the car runs better with the aftermarket replacement sensor is information: it suggests the ECM is getting signal from a functional knock sensor. Indeed, the HSM only describes continuity tests for t-shooting a P0325, so your intuition to test for a fault along the wirepath or the connectors is sensible.

However...

Honda electronics are extremely finicky and don't play well with non-OEM parts. Every Accord/Acura owner who has replaced their IACV or CPS with aftermarket is nodding their heads in silent testimony, and I suspect that's where your gremlin is. I realize a genuine Honda knock sensor (p/n: 30530-P5M-013) is hurty-expensive. Perhaps you could harvest an OEM knock sensor (Denso) from an LKQ or similar salvage yard local to you? Alternatively, you might call Beaver Honda for a part quote.

Props for keeping your stalwart 6th gen on the road for nearly four hundred thousand miles! You've earned quite a lot of equity in that car over these past two decades. So for goodness sakes, treat your beloved Accord to a new Genuine Honda knock sensor!

 

Thanks for the reply, since this first post, I took the manifold off again to check wiring more thoroughly, re-bundled and taped, checked torque on the sensor, etc., etc. I knew it would still turn the light on (which it did after a mile or two test drive), and came to the same conclusion you suggest, which is that it's going to require an actual Honda knock sensor. I found what looks to be a real one on Amazon for $140ish, which beats the $330 my local Honda dealership quoted me. I'll check out the site you posted also.

 

No, it's taken more than a minute the 3 times it's been reset with both KS's. After resetting the computer with an obd2 reader, I drove it around town for a couple days before it came back on. I did keep the rpms below 3k for those 2 days tho, idk if maybe that helped mask the problem somewhat or..?

 

Bleh... dealerships. Avoid dealerships as a policy. ...bleh.

While I believe 30530-P5M-013 is the Honda p/n for knock sensor for your Accord, you should confirm the exact part number against your Accord's VIN.

 

I just called beavers and they priced a used genuine Honda KS for $35 bucks plus shipping. which is a great price, I'm just a little concerned with how fragile it'll be. I guess for 35 bucks it's worth a try. Then again, I'm getting tired of taking the intake off. What to do, what to do... I'll post the final result.

 

Glad you went with a used OEM part. I don't think fragility will be a concern. The overarching idea here is that you want to see if installing a Genuine Honda part makes the DTC disappear.

As a side note, with that intake manifold (IM) off take the opportunity to do some cleaning! Buy a case of brake cleaner and bottle of throttle body cleaner from Walmart, still the least expensive source for these nummies.

- Clean engine with degreaser: Cover the intake ports then douse every nook and cranny. Thoroughly flush the resultant spooge with a water spray bottle.
- Give the IM innards—especially the EGR port—a thorough brake cleaner lavage; remove/clean the EGR valve. Follow Honda TSB99-085 for IM and EGR cleaning procedure.
- Clean both sides of the TB with a spritz of TB cleaner. Don't overdo it lest you gunk up the IACV mounted underneath the TB. Best to read up on proper TB cleaning procedure beforehand.
- Inspect the IM/TB gaskets for cracks; replace if necessary.
- Inspect for oil seepage around the valve covers and camshaft plate; replace gaskets/seals if warranted.
- Inspect every hose—fuel, pneumatic, and coolant—for cracks; replace if warranted.
- Consider replacing the PCV if warranted.

And finally...
Presuming you disconnect the coolant hoses to the TB each time you remove the IM you likely introduced air into the coolant system. This might cause a new issue—idle hunting—(along with its DTC) which will annoy you on a neural level. After you've declared the knock sensor issue resolved, consider doing a proper air purge procedure to the Accord's coolant system.

 

I'm on it, everytime I take the manifold off to tinker with this I go through a cleaning regiment that's borderline obsessive. I might have the cleanest egr path of any accord this age, from plenum to exhaust, and I could eat dinner of off my mating surfaces. That's partly why it takes me days, not hours, to do this job.

Edit: I've been able to evac most if not all of the air in my coolant by filling on a slight incline and utilizing the bleeder on the thermostat housing. I normally check a few times in the following days to see if I can find more air to burp out. The last thing I need is 'idle hunting' and another DTC due to something like that to drive me crazy, which until now I didn't even know was a thing so it definitely would have.