Engine Coolant Bypass Valve
 

I'm still struggling a little with a couple of problems on the S40.

As a brief recap the car began to overheat one day. I topped up and was able to carry on no problem. It now appears that one way or another I am very slowly losing coolant. So one problem is where is the water going - which I haven't fully got to the bottom of.

My next problem is that I get 4 errors with my generic OBDII scanner.

The 1st is a glow plug - so I have just ignored that as the car starts well.
The 2nd and 3rd are the EGR which is unplugged and blanked so I ignored those too.

The final code is P2683 which is "Engine Coolant Bypass Valve Control Circuit High".

I presume that the thermostat has a solenoid or similar? Looking at where the top hose connects to the thermostat there is a yellow electrical connector underneath which again I presume is where the ECU would get the above code from but nothing is plugged into this connector and I can't find any electrical connectors anywhere nearby to plug in.

Can anyone confirm that the thermostat does normally have something connected? And if so where does the wire go to?

It's a 2.0d SE 2004 Euro 3.

Thanks

There is also the coolant temp sensor located rear of engine below high pressure fuel pump.
They only cost a few quid but are a right pig to change

I presume the coolant temp sensor is working correctly and connected as I get an OBD reading of coolant temp which rises accordingly as expected.

Being doing a bit of reading and it appears that the yellow connector has been asked about before and from what I can tell it ended up that the previous poster concluded that it shouldn't have anything plugged in...

http://www.volvoforums.org.uk/showthread.php?t=176190


So if that is the case where should I be looking for an electrical sensor/connection which would give the P2683 "Engine Coolant Bypass Valve Control Circuit High" Error?

The Error shows as a "Current Error" so immediately comes back after clearing it.

Thanks

Have you been reading those codes using the android app "Carista" by any chance? .. I d/n and installed that app 2 days ago and I'm getting the exact same set of error codes as you .. however my car starts, drives, cools and heats up just fine the way it should.

For now, I'm relating that P2683 code to the EGR cooling circuit, because I too have the EGR valve blanked off and disconnected.. this is just my assumption though.

http://i61.tinypic.com/2iqes61.jpg
This is the EGR with it's cooler .. theoretically speaking> since the valve is blanked off and disconnected, temp of coolant entering the exhaust gas pipe bath compartment would remain constant if not higher triggering a combined error report: "2nd and 3rd EGR error codes + P2686"

Thank you Guru - you are a star!

I wasn't using Carista (I tried to as I downloaded it free the other day when it was app of the week - but it wouldn't connect!) - I was using Torque Pro.

So I'll take those 3 fault codes as just being EGR related. Which in that case means that everything seems to be functioning correctly.

The car starts perfectly every morning, can do long journeys with no problems. Power is great etc. My only issue is that I am losing a little water. It isn't a lot that I'm losing. I did fear it was ending up in the oil filler tube but I'm not convinced if it is or if it is just condensation. I'll post up a few more pics in a minute of what it looks like now.

Thanks again - it has put my mind at rest regarding the fault codes! :)

Here is the picture of the oil filler tube and the filler cap. This picture was taking yesterday after the engine had been run on idle (from cold) for approx 15 mins.

The oil filler cap has no white gunk like you would associate with a HG failure. It just has a few droplets of water on it.

The filler tube has a very thin coating of white mist on the bend. The oil itself still looks nice and fresh (not black).

I cleaned the tube out on the 4th May, put an oil flush in and changed the oil and filter. So that is the amount of white that has appeared over the last 43 days. I mostly do short journeys to work of approx 5 mins. I occasionally do longer journeys but they're not that frequent as we have a big 7 seater we use at the weekends etc.

So is that moisture excessive for 43 days?

During that time it has used approx 100ml of coolant.

During that time it has done approx 300 miles. Longest journey being approx 50 miles.

I have confirmed that it is heating and cooling correctly when it gets the chance to, the only reason it got warm the once was because the coolant got low.

I had a look around for any signs of damp, the only bit I could find was this part (image attached).

It isn't dripping off, and doesn't leave any marks on the drive. It is black but didn't really feel like oil. It certainly didn't smell of gearbox oil.

First of all, you're welcome :) but please don't forget that this is only my assumption based on the fact that my car does not suffer similar symptoms, yet this code popped up to on a generic OBD II diagnostic .. any many mechanics would never consider these generic codes to be decisive of anything, the OBD II protocol falls short of determining a true fault.

As for this water in oil issue, I have seen your previous thread and the amount of milky gunk you initially found in there ..

and logically thinking .. it really should be a mutual relationship of exchange between the two compartments, meaning that if water is mixing with oil through a failed HG or a cracked cylinder head, then oil or AT LEAST combustion fumes should be mixing with the coolant also.

What I think you should do is visit your MOT station, or any other service with emissions control facilities, and tell them to measure for Hydrocarbons "HC" in your coolant .. so not by sticking the gas analyzing probe up the exhaust, but by placing it over the neck of the coolant expansion tank after removing the cap, without dipping it of course!

If the air in the expansion tank tests positive for hydrocarbons then unfortunately that would mean that both systems have opned up on each, either through a cracked cylinder head, or a failed HG.

Good luck!

Btw., there are chemistry sets called Combustion Leak Detectors, have a google at that if you wish, If you can't get the coolant expansion tank air analysis done

I've tackled this problem twice on my car .. it's the rear crankshaft seal whch is situated behind the DMF leaking a bit of engine oil, not critical just watch your oil level now and then in case it gets worse, otherwise have it replaced when you do your next clutch/DMF job .. it's only a £20 teflon ring but reaching it means gearbox + clutch + DMF out