Ok, so not even the liquid one is any good? Do garages clean them out, or would they rather replace? It's going to cost a lot to replace, as I think the part alone is a couple of hundred.

I used old brake fluid and a doubled twisted piece of stainless steel wire (hooks one end, loop at the other) to clean the EGR passages.

Took a long time. Eventually I "broke through" and the excess brake fluid drained away.

Brake fluid is a very effective cleaner, but I might hesitate to use it on an EGR valve (which fortunately didn't need cleaning) in case it attacked the plastics. I might hesitate to use oven cleaner as well.

At the very last minute it occurred to me that I might have a hydrolocked cylinder full of brake fluid and I took the plugs out before turning over.

This turned out to be fortunate.

Lots of smoke on startup, and probably not very catalyst friendly, but it cleared eventually

You can check basic valve operation (or at least you could on a Honda Accord of that vintage) by applying voltage to the control terminals and seeing it open .

I have heard of this "paintwork" of which you speak. Might even get some sometime, though it does sound like it might be a bit of a nuisance.

I packed paper towel loosely in the plug wells, and it intercepted the brake fluid that blew out of one of the plug holes. There was a risk of damaging paint inside the engine compartment, but (when I thought of it, which I almost didnt) I considered that more acceptable than the risk of turning over the engine on a hydrolocked cylinder.

I've also heard the "brake fluid burns amazingly well" story.

I daresay it can be persuaded to burn, though I would be rather surprised (maybe even "amazed)" if it burned as well as the (presumably non-chlorinated these days) brake cleaner, recommended above, which is a mixture of volatile hydrocarbons.

Wickipedia has "Rubber and some types of plastics are decomposed by brake cleaners by removing binding components. This has the consequence that the rubber will appear unchanged at first; however, it will become brittle, and after a few weeks to months cracks and fractures appear."

Seems like a bad idea to let that stuff anywhere near your brakes then, and I don't. Maybe I should add EGR valves to that prohibition.

Re "don't let lots drop into/onto exhaust " (about brake fluid) anything you use to clean the EGR path is going into the exhaust, so you kind of have to accept that.

If a brake fluid fire inside the exhaust (?) which is designed for, like, exhaust gases, is a big worry to you, better not use it.

Its so far from being a big worry to me that I'm considering using it to decoke my combustion chambers, though I may try and rig up steam or water mist aspiration instead (or first).

I accept, though, (and said) that it perhaps isnt much of a tonic for a catalyst.

I don't have a catalyst.

Edited by edlithgow on 09/06/2022 at 05:38

I agree that brake fluid damages paint, but I run bangers that already have dodgy/missing paint, so for me its a minor concern.

I'm unsure if brake fluid is a recommendable cleaner for an EGR valve, but I'm even less sure of brake cleaner or oven cleaner, which are recommended above, so if I had to clean an EGR valve I would use brake fluid.

One advantage is that its water miscible, so, having used it, perhaps with a "pipe cleaner" or a dental/interdental brush, you could flush under the tap, and/or use a pressure jet from a hypodermic syringe, maybe finishing off with ethanol or acetone. Water rinsing should reduce the risk of harmful side effects.

This regime works very well with carburetors

You used to be able to get a water-rinseable brush cleaner with apparently similar properties, but I think that is no longer available, maybe for environmental reasons.

Edited by edlithgow on 12/06/2022 at 03:06

OK, I suppose those might be possible UK alternatives for EGR valve cleaning, and may be safer.

Not seen them here, though, and I already have the brake fluid.

The EGR valve itself is not going to be the problem if it moves freely from fully open to fully closed, and if it works correctly when commanded to. What will be the problem is the air intake blocked or restricted with carbon deposits mixed with engine breather fumes forming a thick sludge. The only way to get rid of it is to dismantle the air intake, remove the inlet manifold and thoroughly clean it. I found a 50/50 mix of water and heavy duty traffic film remover is very effective.

Clogged plumbing (though of the EGR path rather than the air intake) was certainly a problem with the Accord, so much so that a US Accord forum member refused to believe it wasn't a diesel, which "we don't get in the US".

The code in that case translated to something like "Insufficient EGR flow" though. The above OP's codes seem to be specific to the EGR valve control circuit, though I have heard that these code thingies can be a bit misleading.

If it does turn out to be intake coking, a catch can might reduce the rate at which it happens.

I've never heard of catch cans on the EGR path but I suppose it might be a (theoretical at least) possibility, though actually plumbing it in might be challenging-to-impossible.

Edited by edlithgow on 15/06/2022 at 03:00