2005 Honda Odyssey engine knock

My wife’s 2005 Honda Odyssey LX has 28,000 (mostly city) miles and the engine knocks at low RPMs. It is not as noticeable at higher RPMs. Any idea what could be causing this? Is there a recommended fix? The van is starting to sound like a diesel!

Is this a knock as in “spark knock”/pinging/pre-ignition, or is it a knock as in bad main bearing/rod bearing?

Describe the sound for us a bit more completely.

Is it worse when the engine is first started?

Is it worse when climbing hills?

Has the engine ever been run with a low oil level?

Has the oil pressure warning light on the dashboard ever lit up, and if so, how far did you drive the vehicle after the light came on?

If your still under a warranty(likely under powertain if not bumper to bumper currently) I would visit your local Honda dealer and go from there. Forget about guessing over the internet.

Better description - loud valves/pinging.

The noise actually seems to get worse after the car has been running for a while.

Not any worse when climbing hills.

The enginer has never been run low on oil and the oil pressure light has never come on.

I agree with Andrew that, if it is still under warranty, you need to get it back to the dealership. And, the dealership will ignore whatever diagnosis you might give them, as they have to go through a standard diagnostic protocol with your van.

However, if I was to take a guess, I would say that your EGR valve is probably in need of cleaning or replacement.

The EGR valve runs a little exhaust gas back through the engine. This helps to lessen ping conditions. When the EGR passages get plugged with soot, ping is more likely. The knock sensor stops ping from happening, IF the ping conditions aren’t too great. If the knock sensor isn’t working, or the ping conditions are too great, the engine will ping. To raise the ping thresh-hold, use higher octane fuel. You have been using the car maker’s recommended octane fuel, haven’t you?