Right, I had an fault code come up, P0401, EGR valve, inadequate air flow. The car is a 55 registration Octavia 2 with 40,000 miles on it. So reading the pool of wisdom that is Briskoda, it seemed most likely that the EGR valve needs a clean.

So, I removed the cover from the top of the engine and set about removing the allen bolts from the underside of the EGR valve and the flanged pipe on the side. I dropped the allen key once and it came to rest on the tray under the engine and was retrieved after a brief sweary interval. I then got a length of copper wire and tightly twisted one end around the allen key; I wasn't going to get caught out again.

Now, the last bolt is behind the EGR and is awkward, required six fingers with double joints. To make room I disconnected the crankcase breather hose from the EGR control valve, moved it to one side and continued trying to get the allen key onto the set screw. At some point, I had the allen key upside down; it slid smoothly through the loop of copper wire, clattered off the EGR valve and vanished.

Now, this is the difficult bit; I think it may have gone down the crankcase breather hose.

This isn't funny. Stop smirking, you. Anyone laughing will be taken outside and shot.

I've cautiously fished down the hose with a magnet but didn't catch anything.

So the question is, can anyone who is familiar with this engine tell me what's on the other end of the hose? Is there a valve, mesh, u-bend or breather, or where might the allen key come to rest? Does it go straight into the side of the crankcase? Is this a sump off job? It's due an oil change anyway so taking the sump off isn't a major crisis.

I'm not starting the engine until I've found the allen key, which is a bugger. I'll just have to use one of my other cars for a while.

um kinda hard to know what pipe you are talking about here, but if its the big black one below the EGR, that would be an intercooler hose matey AFAIK

Big black flexible rubber type hose, about 60mm in diameter, comes from below, connects to the underside of the EGR control valve (I think) , which is bolted to the bottom of the EGR valve. It's the EGR hose or a crankcase breather, judging from the oil in it.

Large diameter rubber hose sounds like the air intake from the intercooler to the manifold. The oil in it will be from the turbo (perfectly normal).

Yes, you're probably right, it's the biggest hose going to the inlet manifold. Presumable the exhaust gas comes up the smaller metal pipe.

Presumably, this goes from the turbo under the engine and back up to the manifold; the allen key will be at the bottom of the pipe, not in the engine.

Yes very likely it will be sat at the bottom of the pipe.

I retrieved the allen key. The hose is the air intake coming from the intercooler, so my initial fear that the key was in the engine wasn't justified.  The allen key had bounced most of the way along the hose and was near the intercooler connection. I retrieved it with a magnet after undoing the bottom hose union.

The ERG valve was thick with solidified oil deposits, literally 5 or 6 mm thick in places. Is this typical? This must be oil passing through the turbo bearings and then into the air stream going to the intercooler.

  I cleaned and reassembled the EGR valve and deleted the error codes, but the diagnostic light came back on within 10 miles.  Does this require a new EGR valve, or could the problem be caused by something else? Should I get the EGR valve tested first, or just cough up for a new one?

Any wisdom on this will be greatly appreciated.

having deleted the original DTC have you checked to see what code is now present?

The P0401 code for inadequate air flow is only a detection by the EGR, its could be that there is a restriced air flow prior to the EGR itself.

The DTC could be caused by a number of other issues such as EGR gas temp sensor, vacuum or EGR hose disconnected, open or short in vacuum circuit for EGR, EGR valve stuck closed or even the engine control module.

You could ideally do with some live frame data to assist!

have you also seen this previous thread; http://www.briskoda.net/forums/topic/173457-p0401-egr/

P0401, as previously.

The EGR valve seems to be what I know as a diaphragm operated butterfly valve; a vacuum on the tube should move the vane. Blowing down the tube meets with little resistance, so this (IMHO) would suggest the diaphragm has failed. Any one know otherwise?

  Thanks O_ptic, I will read that.

I retrieved the allen key. The hose is the air intake coming from the intercooler, so my initial fear that the key was in the engine wasn't justified. The allen key had bounced most of the way along the hose and was near the intercooler connection. I retrieved it with a magnet after undoing the bottom hose union.

The ERG valve was thick with solidified oil deposits, literally 5 or 6 mm thick in places. Is this typical? This must be oil passing through the turbo bearings and then into the air stream going to the intercooler.

I cleaned and reassembled the EGR valve and deleted the error codes, but the diagnostic light came back on within 10 miles. Does this require a new EGR valve, or could the problem be caused by something else? Should I get the EGR valve tested first, or just cough up for a new one?

Any wisdom on this will be greatly appreciated.

told ya

the crud is mainly caused by fumes coming from the exhaust (EGR = exhaust gas recirculation) mixing with oil coming from the breather hose at the top of your engine which connects to your air intake pipe, for double laughs, remove your intake manifold while you are at it and have a peek

regarding your fault code, is the vacuum pipe thats used to operate the EGR valve connected properly, if so its likely that its failed Im afraid. your options will be replacement or removal, replacement being the cheaper option...

told ya

the crud is mainly caused by fumes coming from the exhaust (EGR = exhaust gas recirculation) mixing with oil coming from the breather hose at the top of your engine which connects to your air intake pipe, for double laughs, remove your intake manifold while you are at it and have a peek

regarding your fault code, is the vacuum pipe thats used to operate the EGR valve connected properly, if so its likely that its failed Im afraid. your options will be replacement or removal, replacement being the cheaper option...

You did tell me. New EGR valve then I fear. There were oil deposits in the big air hose coming from the intercooler, which is what had caused me to think it was the EGR hose. The flanged metal pipe connecting to the EGR valve from the left must be the EGR (or crankcase breather), but this seemed relatively clean. I didn't look too closely, but it seems I shall have to revisit this. Does this suggest there's excessive oil in the air from the turbo (bearings?) , or does this sound normal? I've never had reason to get intimate with a turbo before. The vacuum pipe is secure and airtight, but I'll check it over before I part with money for a new EGR.

You did tell me. New EGR valve then I fear. There were oil deposits in the big air hose coming from the intercooler, which is what had caused me to think it was the EGR hose. The flanged metal pipe connecting to the EGR valve from the left must be the EGR (or crankcase breather), but this seemed relatively clean. I didn't look too closely, but it seems I shall have to revisit this. Does this suggest there's excessive oil in the air from the turbo (bearings?) , or does this sound normal? I've never had reason to get intimate with a turbo before. The vacuum pipe is secure and airtight, but I'll check it over before I part with money for a new EGR.

I wouldnt worry about the oil deposits, thats normal. You may be able to get a reconditioned EGR for less money, or consider one from Ebay? if your car was mapped I would suggest an EGR delete kit.

If you didn't do the inlet manifold, I'd strongly suggest doing it on any PD140.

The PD170 you have to be a bit more careful due to swirl flaps, but these are not on the PD140 (IIRC)

Anyway, that will be chock full of crud too :(

All done (touch wood). New EGR valve from Eurocarparts for £60, fitted today, the fault light has stayed off so far.

The diaphragm on the old EGR valve had perforated, blowing down the vacuum hose connection on the new one meets a dead-end, the air doesn't escape as on the old one. I should have binned the old one at the outset instead of trying to clean the filthy, minging thing.

I didn't do the inlet manifold, but now I'm more familiar with it, I may do it in the future.