engine coolant bypass valve fault P26

[Gowz66]

Mine has just done this diagnostics say engine coolant bypass valve A. Took it to dealer and they didn’t want to know as warranty ran out last week!!!!! So, can anyone tell me the part number and where it is located on the engine please?

Hi, had the same issue with mine this week. I bought the new valve from my local dealer. Not cheap £219. When you take off the under tray, the valve is located just in front of the passenger wheel. There’s 3 small pipes coming off it and an electrical connection on the top. See part number and pic of the valve below. Hope this helps.

 

[The Vee]

Just seen this and thanks for taking the trouble to give all that info. Same as you, I did manage to replace it some time ago but still find VW’s response very very poor.

 

[Rapids]

Hi, had the same issue with mine this week. I bought the new valve from my local dealer. Not cheap £219. When you take off the under tray, the valve is located just in front of the passenger wheel. There’s 3 small pipes coming off it and an electrical connection on the top. See part number and pic of the valve below. Hope this helps.View attachment 275656View attachment 275655View attachment 275656View attachment 275655View attachment 275654View attachment 275652

Have the same issue myself, van 1 week over warranty and was told by VW that once the warranty date is exceeded the van is deleted automatically from the system. Fact is this part is clearly causing issues with a lot of owners and if its not a recall in my opinion. it should still be dealt with by VW.
The above pics and info are a great help as VW could not give me the part number and merely sent pics of the coolant system for me to identify. Will have to do the job next week, is it straightforward, was bleeding the coolant system any issue when refilling ?

 

[The Vee]

Didn’t have too many issues. Hose clips can be tricky as they are the springy compression type. Didn’t lose too much fluid but as long as engine is cold do not remove header tank cap until job done. This will prevent some loss of coolant. When topped up afterwards leave ignition turned on but do not start engine it will go through a self bleeding process until warning goes out. Check level top up and start. Usual disclaimer (!) this is how I did mine and it’s fine, but I’m not a Vee Dub tech. U

Have the same issue myself, van 1 week over warranty and was told by VW that once the warranty date is exceeded the van is deleted automatically from the system. Fact is this part is clearly causing issues with a lot of owners and if its not a recall in my opinion. it should still be dealt with by VW.
The above pics and info are a great help as VW could not give me the part number and merely sent pics of the coolant system for me to identify. Will have to do the job next week, is it straightforward, was bleeding the coolant system any issue when refilling ?

 

[The Vee]

Forgot to mention, make sure you have released any pressure in system first on the cold engine.

 

[Rapids]

Didn’t have too many issues. Hose clips can be tricky as they are the springy compression type. Didn’t lose too much fluid but as long as engine is cold do not remove header tank cap until job done. This will prevent some loss of coolant. When topped up afterwards leave ignition turned on but do not start engine it will go through a self bleeding process until warning goes out. Check level top up and start. Usual disclaimer (!) this is how I did mine and it’s fine, but I’m not a Vee Dub tech. U

Thanks for that appreciate the tips, seems with the way technology has gone you have to research first to avoid any pitfalls

 

[Rapids]

I had same issue P26 coolant diverter valve, warranty was out by a week and they weren't interested in accommodating me. Light has been on about 2 weeks while I was trying in vain to get some good out of Vw. Eventually got fed up and bought the valve 275 euro, planned to fit it tomorrow. Within 20 mins of buying the valve the light has gone out and has not returned as yet. Anyone had this experience. ?

 

[Robert]

Don't you worry, it will come back.
I do recommend to proceed with the replacement as planned.

Friend of mine experienced this

38703 - Engine Coolant Bypass Valve 1
          P26B1 00 [00100000] - Stuck Closed
          [Engine Coolant Bypass Valve "A" Stuck Closed]
          Intermittent - Not Confirmed - Tested Since Memory Clear

38704 - Engine Coolant Bypass Valve 1
          P26AB 00 [10101100] - Stuck Open
          [Engine Coolant Bypass Valve "A" Stuck/Open]
          MIL ON - Intermittent - Confirmed - Tested Since Memory Clear

on his T6.1

Engine (J623-DNAA)
SW: 05L 906 023 D  
HW: 05L 907 309 F
R4 2.0l TDI   H80 1351

so I helped him to replace infamous coolant bypass valve.
03N 906 249 G -> O3N 906 249 K
View attachment 276806
These faults were caused by the failure of internal sealing and effectively coolant ingress into electrical section.
Fingers crossed for the revised version to last for good.

 

[whodat]

Yes, mine was on and off randomly until the unit got changed (under warranty).

 

[Rapids]

Don't you worry, it will come back.
I do recommend to proceed with the replacement as planned.

Yes Robert it did reappear, fitted new valve yesterday

 

[Rapids]

Don't you worry, it will come back.
I do recommend to proceed with the replacement as planned.

Hi Robert, friend of mine said he has done quite a few of them and can be done in half an hour ! . Took me 3 hours, biggest problem was the spring clips breaking and being partially glued to the pipes. Anyway got there in the end. Got some great advice of this site. Its a real goldmine. Thanks for the advice. Mark

 

[Changabang]

I have the same issue. Engine warning light (orange) came on on the way up to Scotland. Took the van a T6.1 20000 miles to VW Inverness who diagnosed P26AB00. Coolant bypass valve 'stuck open'. Then another fault code 'stuck closed'. They said it was OK to drive it home, which I did, but not before spending a week on the west coast. Home is in Bournemouth 643 miles away. No issues getting back.

 

[Rapids]

I have the same issue. Engine warning light (orange) came on on the way up to Scotland. Took the van a T6.1 20000 miles to VW Inverness who diagnosed P26AB00. Coolant bypass valve 'stuck open'. Then another fault code 'stuck closed'. They said it was OK to drive it home, which I did, but not before spending a week on the west coast. Home is in Bournemouth 643 miles away. No issues getting back.

It does not appear to effect engine temp. Mine was gone for a few weeks before I replaced it. It is in front of the passenger front wheel. Took me about 3 hours to do it but if I had to do it again I could half the time. If you need any info let me know and I'd be happy to help. I got some great help on this site

 

[whodat]

When I had the problem the oil temp would reach upto about 105C to 110C.
On the same run after the fix it doesn't get above 100C. Not a lot of difference but definitely noticeable. I've not seen temps above 101 or 102 I think since then.

 

[Changabang]

Can confirm no change in engine temp. Oil temp is a more interesting 'thing'. My van has always run at between 100c to 110c. In the Alps last year up and down the hills it was often 115c to 118c. This may reflect how heavy a van is. Mine is a kitted out as a camper and is probably quite heavy when full loaded for a trip. Feels heavy on the accelerator anyway. Has anyone got a part number and price for this valve please?

 

[Changabang]

Found the part number. Thanks.