Got this code after a hard cruise for 6 miles at about 110mph.
Cold morning, 3C, and the car ran perfectly and continues to do so.

Standard 2004 82K mile facelift apart from a 'Fujima' cold air intake.

Cleared the code when home with my cheapo Chinese OBD reader, and it hasn't come back in the last 4 weeks since.

Anyone else had this? Maybe just dense cold air temporarily making the engine lean and pinking? I use Shell V-max, so wouldn't expect this. How far can the standard EMU compensate with a cold air intake?

I've read about the horrors and expense of knock sensor replacement, so I don't want to go there unless necessary.

Any advice welcome, or shall I consider the code clearing as a 'fix'

 

Wait for it to come back.

 

Confucius say: problems that go away by themselves, come back by themselves.

I currently have the same code once the engine has either idled for more than
A couple of mins, or it revs over 3k. I have a replacement waiting to be fitted.

 

Cheers, I've bought the deep socket, but will hold off buying the sensor until or if the fault goes hard.

 

If you were driving at a steady cruise then the engine would probably revert to closed loop mode and will start leaning off the mixture via the lambda sensor readings. If the mixture leaned out too much the knock sensor is your fail safe and then retards the ignition. If you have a dying lambda sensor it can react slow or give dubious readings. Maybe the engine is leaning itself off too much via the lambda sensor readings.

I had a lambda sensor fail in the rich position on an old car and it didnt have a knock sensor fitted and the pinking split one of the cylinder liners.

I wouldn't be overly worried just keep in mind if the light comes up again then its more than likely caused by knock and you want to ease of the engine for abit. If it becomes more frequent then its something you defiantly want to look into getting fixed.

 

Lambda will always fail lean / low voltage, but this then causes the ECU to overfuel rich to try and compensate.

 

From experience on a 90k and a 65k engine they seem to get very brittle and the plastic easily breaks off. I broke both my knock sensors as a result when doing my engine swap. It could be hanging on for dear life due to heat cycling. Either way if you go to remove the multi plug on it you will snap it without a doubt so have a new one ready. CFL Honda in Florida is your best bet, £75 delivered to your door via FedEx including taxes.

 

As predicted above, the light came back on today with the same code.

This time it came on at half throttle up a steep hill in 3rd at about 3K revs. About 10C as well, so my cold/lean theory looks less likely.
The engine has 82K miles on it, so as suggested, it could be the lambda sensors or knock sensor itself.

It was a bumpy road, so what's the chance of it being a loose wire or connector?

If it ever stops raining, I'll spent some time checking it out.

That price from Florida is less than half RRP from Honda!
If I do need one, I'll get onto them.

Cheers for all the advice.