Last June we bought a '99 Accord with about 103k miles. We drove it to Pennsylvania (1500 mile trip), and to Wyoming (4000 mile trip) last year. I discovered that the head gasket was bad after these trips and did a head job on it. I followed the book for removal and install etc. No problems there, except that I broke off the knock sensor and had to buy a new one. The head had to be milled to get it back to flat. I don't know how much they had to remove, but its a reputable shop, so I'm sure it was still in spec. The check engine light came on before the head job with an occasional misfire code, I guess antifreeze doesn't fire as well as gas . Anyway, after the head job the CEL will come and go. Always the same code for the knock sensor. So, my question is, could the reduced size of the combustion chamber due to the milling be causing extra heat in the head and detonation. If yes, would putting colder spark plugs reduce it. Sorry for the log windedness. Thanks for any responses.

 

Was the sensor an OE or aftermarket sensor?

When the head was replaced were the plugs replaced, if so do you know what brand?

 

What code came up? We have seen many get a bum steer from assuming a code number told them by a 3rd party.

Does CEL appear immediately after startup or only while driving? If immediately, there may be an electrical fault; connector, wiring, sensor, or ECU.

Is car actually pinging that you can detect? I've seen pinging caused by lack of EGR flow (too hot combustion chamber, amazingly EG actually cools combustion). Also it might be worth experimenting w/ higher octane to see if that stops code from appearing.

good luck

 

Sorry so long in responding. The plugs are OEM NGK plugs. I can't remember the number. The sensor was aftermarket. I have a code reader, I can't remember the number right now, but it is always the same one for the knock sensor. The CEL comes on while driving. It will stay on for a few days, then go off for a few days and so on. The car runs very well when the light is not on, not quite as well when it is on. I assume that the computer retards the timing when that code is active. I can't ever actually hear any pinging. Thanks for the responses. I want to get this fixed. Its like a "splinter in my mind."

 

The correct code should be P0325. This could be either a fault in the sensor, connector, wiring fault, or ECU fault. Suggest confirming before any further efforts.

Easy, but expensive diagnosis is to replace the knock sensor and see if that fixes the problem.

Hard, but possibly less expensive, is to check the connector and wire between the ECU connector and knock sensor connector for continuity. Ground one end to body and check that other end also is grounded. If open you have a fault in wire or connector somewhere.

I did not see any diagnostics for the knock sensor itself. It said to replace after confirming wiring was good.

good luck